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Geology

What is Concrete?

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What is Concrete?

Concrete Blocks
Photo by uve sanchez on Unsplash

Ever notice that just about every building has a concrete foundation?  There is a very good reason for this and it is not about aesthetics. Concrete has enormous compressive strength, meaning that it is an excellent material for holding up the weight that is above it. 

Concrete is not just used for foundations, but also for columns, and beams. slabs and just about anything where there is a load-bearing issue. Load bearing means an element that supports the weight above it. The amount of weight that the load-bearing element would support would depend upon how many concrete columns (or other concrete supporting materials) are available to support the whole load.

For example, a 30-story building has 10 supporting columns on the ground. That would mean that the weight is evenly distributed across each of the 10 columns or mathematically speaking, each concrete column would support 0.333 (10/30) of the load (building).

Another probably more identifiable example is the load-bearing walls in a house. If you live in a house, you have probably become aware of where your load-bearing walls are. These are the walls that actually hold up the house; however, for frame houses, concrete is not the usual load-bearing material, but heavy wood or steel instead. 

A concrete column
Concrete column supporting the highway above. Photo by SS

In short, concrete is an excellent source for withstanding the heavy forces that are above it or more specifically, as an excellent compression material.

Did you know that concrete also gains more strength as it ages? With that said, let’s take a look at just what this compressive material is actually made of.

What is Concrete Made Out of?

Concrete is a mixture of air, water, sand, and gravel and the percentages of these elements are usually 20% air and water, 30% sand called fine aggregates, and 40% gravel, with 10% being cement; that is, 10% being the ‘glue’ that keeps all those other materials together. Remember, from our article on cement, it is just the binding material for the assembly of concrete. When the cement is mixed with water, it is called paste. 

This proportion is called the 10-20-30-40 Rule; however, the exact percentages of the materials can vary depending on the combination of the concrete mixture, including the type of cement and other factors that we will explain in this article.

How are the Proportion of Materials that Form Concrete Determined?

So we know that concrete is a mixture of paste and aggregates and sometimes rocks. The paste coats each of the aggregates and as it hardens (the process is called hydration), concrete is born until it becomes a rock-solid mass, capable of withstanding a load much heavier than itself, but if the proportion of water and paste is not correct, this rock-solid mass can deteriorate causing unwanted and potentially dangerous consequences.

The trick is to carefully proportion the mix of the ingredients and much of it depends on the ratio of water to cement and this ratio is calculated by the weight of the water divided by the weight of the cement. A low water-content ratio yields high-quality concrete, so it is best to lower the ratio as much as possible without sacrificing the integrity of the concrete.

If the ratio results where there is too much water in the mixture, the aggregates become thinned out, resulting in weakening the concrete and we can figure out what that would mean.

Conversely, If there is not enough water in the mix, the water will evaporate too fast, compromising the integrity of the concrete and resulting in it being weak as well.

Construction worker worket pours concrete into rebar frame
Construction worker pouring concrete into steel rebar frame. iStock

What is the Strongest Concrete Mixture Ratio?

1:3:5 which is cement and aggregates (in this case, the aggregate is broken into sand (3) and gravel (5), and this is considered the ratio that would create the strongest concrete.

What Happens if the Wrong Mixture of Concrete is Used?

If the ratio of the concrete mix is not done correctly, there can be a variety of problems, such as compromising its integrity which can lead to disastrous results.

Cracking

Excessive water content, inadequate curing, or incorrect proportions of cement, aggregates, or water can contribute to cracking. These cracks can compromise the durability of the building and allow moisture penetration, leading to further deterioration over time.

Reduced Strength

Concrete strength is a critical factor in ensuring the structural integrity of buildings. If the concrete mix has an incorrect ratio of the required additives, it may not achieve the strength needed to maintain its load. This can compromise the load-bearing capacity of the structure and lead to collapse or deformation under normal loads.

Ultimately, using an improper concrete mixture poses safety risks to occupants and users of the building. Structural failures or deterioration can lead to accidents, injuries, and even loss of life in severe cases.

Champlain Towers Building Collapse

Surfside florida condo collapse
Miami Beach Surfside, FL, June 26, 2021, Champlain Tower collapse most probably due to concrete deficiencies.

One recent incident occurred in Surfside, Florida where the Champlain Towers collapsed on June 24, 2021, and 98 people lost their lives.

The investigation is still ongoing but they have found structural defects in the design of the pool, as well as compromised integrity of the columns that supported the building.

How Much Time Is Allocated Before the Finished Concrete Is Used at the Construction Site?

There is a limit to how long the concrete can be poured after it is mixed. In the US, the limit is 60 minutes from the time the water mixes with the cement to the time of delivery to the construction site.



A safe time frame is up to 90 minutes, then the integrity of the concrete will start to deteriorate. That is why we see concrete mixers right at the construction site as no time is lost between the mixture and the pouring.

What About Reinforced Concrete?

As the name applies, when steel (usually using steel bars, called rebars) is placed inside the slab where the concrete is going to be poured, it reinforces the strength of the concrete.

How Does Rebar Reinforce Concrete?

We have been discussing compression strength; that is, how strong the material is when a heavy load is placed on it, but we haven’t discussed tensile strength, which is the opposite of compression.

Tensile strength represents the strength a material can endure when a force tries to pull or stretch it out. The reason why compression is so important when using concrete is that that is its main purpose – to hold up heavy loads, but concrete does have a limit on how much pull can be leveled on it as well, and there are situations where the tensile strength of concrete is put to the test. The weather being one factor, but there are more.

Enter Steel

Reinforced Steel Slab
A construction worker working on a reinforced steel slap where the concrete will be poured. Photo by SS.

By integrating the rebars inside the concrete, the concern about stretching the concrete is greatly minimized. The combination of concrete and its accompanying reinforcing steel bars successfully manages these situations, because of steel’s high tensile strength; hence, you have a perfect storm of compressive and tensile strength in reinforced concrete (RC).

What Happens if the Reinforcing Steel is Not Inside the Concrete?

Cracking of the concrete surfaces can occur, subsequently causing aesthetic issues, but if the tensile yield is really great, (e.g. a strong pull on the concrete) the situation can become unsafe, so without the steel rods to compensate for this pull, you will find cracks in the concrete or worse.

Conclusion

Concrete is a mixture of sand, water, aggregates and cement. The amount of any of these elements will determine the strength of the concrete. Timing also plays a role as the concrete must be readily mixed within 90 minutes max, but 60 minutes is the usual requirement before being poured into its foundation or another element such as a column or slab.

By placing steel bars which is a mesh of steel wires (rebar) inside the concrete, the tension issue is resolved by aiding the concrete under tension.

So the next time you are walking in a building, especially a large structure such as a skyscraper, give thanks to the materials that allow you to be there, as well being thankful to the engineers who allowed it to happen!

 

Geology

How Cement is Made?

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What is Cement?

Solider pouring the fine powdery cementIf you were to say “I tripped on a cement block”, would you be wrong?

The answer is yes because there is technically no such thing as a ‘cement’ block, but there are concrete blocks; that is to say, cement is nothing more than the ‘glue’ that binds the materials that make up the concrete block, which is usually sand and gravel. So if you were to say “I tripped on a concrete block”, you would then be correct.

According to Wikipedia, cement “sets, hardens and adheres to other materials to bind them together.” In simple terms, cement is the centerpiece of what keeps the concrete intact. 

What Materials are Cement Made of? 

The sand and gravel are called aggregates, and it is these materials that are bound together but remember, cement is not the material, it is the glue. So what makes up the cement? 

The ingredients are mainly limestone and clay, which are extracted from quarries from around the world. Of course, the process of making cement is not that simple. The limestone is heated with clay to 2,640 °F in a kiln (an insulated chamber). This process is called calcination, which liberates molecules of carbon dioxide from the calcium carbonate (the main ingredient of limestone) to form calcium oxide, commonly referred to as quicklime. 

It is here where the quicklime chemically combines with the other materials to make a hard substance, called ‘clinker‘. Gypsum is then added to make Portland cement, the most common type of cement used, which is referred to in the industry as OPC. 

How does the Limestone Mixture Process Work?

The limestone rock is crushed in a machine appropriately called a crusher which reduces the limestone to a size of about six inches maximum. It is then fed into the second crusher where it is further reduced to under three inches. The mix is conveyed and then sent to a raw mill bin to be ground down even further.  

In these bins are two chambers. One that dries the limestone and clay mix and the other that grinds it via hot gasses. Then, once all dry, it is moved to the grinding chamber called a ball mill.  Here a cylinder contains steel balls and rotates which causes the balls to fall back into the cylinder and onto the limestone mix; hence, grinders. 4 to 20 revolutions per minute is the general rotation of the cylinder, which is dependent upon the diameter of the ball mill.

A Newcome Engine

What’s left when the grinding process is done is a product of fine and coarse material. The coarse material is useless in that state and is called reject where it is returned back to the ball mill for additional grinding. A machine called a separator does this part. 

Having the limestone and clay grounded down to a fine powder is still not enough to complete the cement process. The mixture must then enter a device called a cyclone which is used to separate the fine grounded material from existing gases that still exist in it.

Then, the hot gas and fine materials enter a multistage “cyclone”. This is to separate the fine ground materials from the gases.

The result – a clean, fine powdery material and is renamed kiln feed. 

Next, the feed is heated via a process called sintering, which is when the chemical bonds of the material are broken down using heat, and once complete, a new substance is formed called clinker.

Clinker nodules for the production of cement
Clinker nodules produced by sintering at 1450 °C. This is the intermediate process for the production of cement

The clinker is initially very hot and contains small, dark gray nodules from 1mm to 25mm in size where it is placed into a grate cooler for cooling from approximately 2550 °F to approximately 240 °F via the use of cooling fans.

And voila! You have cement!

Final Note

Other elements are added to the clinker depending upon what the cement is going to be used for. In the case of Portland cement, gypsum is the additive.

And you thought that making cement was just adding powder and water. We hope you gained some good knowledge as to how cement is actually created. And the next time you get angry after you trip over a block that’s made up of limestone and clay, you know that it is concrete you take your anger out on and not the cement that put it together.

 

 

 

Geology

How Buildings are Constructed Along Earthquake Fault Lines

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Transamerica Pyramid San Francisco
Earthquake resistant Transamerica Pyramid, San Francisco. Photo Wikimedia CC

One of the first structures built to withstand an earthquake was the Transamerica Pyramid, also called the Transamerica Tower. In this seismically active region, no engineering was spared to keep the building safe from earthquake tremors.

Located on 600 Montgomery Street, it rises 853 feet and 48 floors and was the eighth tallest building in the world in 1972. On the highest floor, 48, there is a conference room that has unobstructed 360-degree views of the San Francisco Bay area.

The building has a wide base that narrows upwards, much like the churches and buildings of antiquity, which is designed to give the structures their stability. No doubt this is an optimum method for buildings that reside along earthquake fault lines. From an environmental perspective, the pyramid design (hence the name), allows natural light to filter down to the streets below.

Looking to limit the degree by which the structure would twist and shake during an earthquake, engineers used a unique truss system with built-in steel, reinforced concrete, precast quartz aggregate and glass. It has two angular setbacks working their way up to the top of the tower and a 212-foot spire. There are two angular concrete structures on the east and west sides that protrude from the 29th floor rising upwards called wings. The wings are part of the structural engineering that went in to keep the building sturdy during an earthquake, but they also have a function. The eastern wing serves as an elevator and the western wing includes a staircase.

To reinforce the building even more, there is a truss system on the ground and lower floors which are designed to support both vertical and horizontal stresses. Truss designs are cross beams engineered to perfectly distribute the weight of a structure in order to withstand tension (pulling) and compression (pulling) forces.

Modern building with external truss system
Buildings with external truss systems are able to manage torsional (twisting) forces generated by seismic events. Photo by Ricardo Gomez Angel on Unsplash

Under the truss, beams are X beams over the ground floor, designed to brace the building against any type of torque movement.

This torque and stress reinforcement was tested in 1989 during the .71 magnitude Loma Prieta earthquake. The building successfully withstood the quake with no damage and no injuries.

 

In addition to above-ground stress reinforcement, there is an additional basement from earthquake tremors, consisting of a 9-foot deep concrete mat foundation, which lies on top of a steel and concrete block that goes 52 feet underground. This foundation contains 16,000 cubic yards of reinforced concrete, including over 300 miles of steel reinforcing rods. This concrete assists with the additional support of Compressive stress and tensile stress.

The Pyramid is a self-contained structure, which has its own 1.1-megawatt power system. Construction began in the fall of 1969 with the first tenant moving in in 1972 and is still standing gracefully today as a monument to earthquake building construction.

 

Geology

The 2 Methods to Building a Subway

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Subway tunnel construction in NYC
Subway tunnel construction in NYC  (Photo: wirestock – www.freepik.com)

For those who love big cities (and even smaller ones), there’s no doubt you have ridden on one of their mass transit lines. With that said, have you ever wondered about the amount of engineering that has gone into building one? Well, here we will give you some basic information as to how they are constructed.

There are two basic methods to subway construction: “cut and cover” and the other is called “deep bore.”  Cut and cover refers to the complete opening of the street, down to where the subway would be built and deep bore refers to the burrowing strategy previously discussed in our Tunnel Boring article.

To determine which method is going to be used, an engineering and environmental review is necessary, which includes logistics, underground water determination, earth material, demographics and of course, costs, not to mention the bureaucracy of working with the different city agencies to determine where all the utility lines, water pipes and potential other tunnels are located. 

This bureaucracy alone could take months or even years, And if any of these factors become obstacles, then additional planning would be required. The bottom line is that this whole procedure is a great undertaking and can get very complex. 

So with this introduction, let’s delve into describing the engineering process by which each of these methods would be used.

Cut and Cover Method of Building a Subway

Tunnel cut and cover method of construction of the Paris Metro
Tunnel cut and cover method of construction of the Paris Metro – Wikipedia Public Domain

This method is found in the building of some of the older subway systems, such as the Paris Metro, London Underground and the NYC subway. With this method, the pavement of the street is completely removed and then a hole is dug down into the ground. 

“Cut and cover” is considerably cheaper than the “deep bore” method; however, the dig must parallel the street, so there is no room for more sophisticated planning, like curved tracks that fork off to some desired locations, unless the street above does the same.

Another undesirable factor is that “cut and cover” results in large holes in the street significantly causing traffic nightmares, as well as major inconveniences for store owners along the route.

Deep Bore Method 

The boring machine is a sophisticated and expensive apparatus that cuts through the underground dit by using circular spinning blades. The advantage this has over “cut and cover” is that they do not have to follow the street grid above, allowing much greater flexibility in the design of the subway lines, as well as not have to dig big holes along the route. The boring method is slow, but efficient and cuts through the earth at a rate of about fifty feet per day. 

The disadvantages are that the costs are significantly higher than cut and cover, where $150 million would be a medium price. 

How the Subway Construction Method Is Decided

As mentioned, there are so many factors to consider when building a subway line, but the number of subway lines and the cost factors involved would be the major considerations.

For example: After extensive analysis of which method would be better to construct the Second Ave Subway in Manhattan, it was decided that the TBM would be more efficient, based upon the fact that cut and cover would cause so much economical damage, the boring method would be more practical, even though it is more expensive.

Preparation for TBM cutting head to be lowered into a tunnel
Cutting Head of a boring machine being lowered into the hole where a tunnel is to be constructed. Photo by david carballar on Unsplash

Just lowering this giant machine into the tunnel is a major task, not to mention expense, but it is worth it in the case of big-city construction.

Another major consideration was the amount of interruption and financial damage the cut and cover method would have caused, especially on a congested and commercial road like Second Ave. where the upper east side and midtown Manhattan would be commercially interrupted.

Considering how often there would have been complaints, especially in this time period, where community demonstrations are the norm, more and more TBM usage is becoming the preferred method, so as not to disturb life above ground. However, cut and cover construction may still be considered if the soil conditions are not up to standard.

Building the Second Ave Subway NYC
TBM in action during the building of New York’s Second Ave Subway (Google CC Flicker)

An example of how the political consequences of cut and cover road disruptions can escalate, take a look at Vancouver B.C.’s recently opened Canada Line. A lawsuit was taken against the city of Vancouver and the plaintiff, a retailer with a store along the subway route where won C$600,000 after cut and cover caused major financial hardship. Following that lawsuit, an additional 41 plaintiffs have taken legal action to recover financial damages. 

What the Future Holds

We are now in the 21st Century and with technology streaming at a rocket pace (e.g. artificial intelligence, at home video conferencing, sending a man to Mars) it will only be time before new engineering technologies will lead to faster, lighter and much less expensive boring machines. Then if you think some cities have excellent transportation facilities now, wait till these new machines come along and open the door to even more elaborate and reduced financial expense.  

 

 

Geology

Green River Formation Fossils and How They Materialized

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Small fossil found in the Green River Formation
Photo: Pixaby

Green River Formation – Overview 

The Green River Formation is a geological pattern that records the Eocene‘s details (a period on the Earth that lasted from 56 to 33.9 million years ago). This fossil formation records evidence of life in a collection of lakes between mountains in three basins, known today as the Green River that flows in Utah, Wyoming, and Colorado. 

Throughout its far-fetching lifetime, this water system is home to the largest accumulations of lake sediments and fossils worldwide. It extends for more than 25,000 square miles and reaches a depth of 2,000 feet or more; the Formation includes 14 different members (represented by different places in location and time). 

The sediments on the river bed are deposited in ultra-fine layers. Each layer has a dark covering along with a light-hued inorganic layer of sediment. Each pair of layers is known as a varve, which reflects different years. 

Green River Formation – Members 

Haddenham Cabin, Fossil Butte National Monument
Fossil Butte  Haddenham Cabin Photo: Wikipedia CC

Being the smallest and shortest-lived on the Green River Lakes, the Fossil Lake was preserved for two million years and is marked by three sedimentary Members. 

  • The Angelo Member – The Angelo member is the youngest member of the Green River Formation. It was too salty to allow aquatic life, so it contains the least remains. 
  • The Fossil Butte Member – The Fossil Butte member is sandwiched between the two members; Angelo and Road Hollow. It contains a record of a more significant number of aquatic species, including plants and animals. While it only represents a few tens of thousands of years, this member’s sediments contain the richest record of fossils from various aquatic organisms. The evidence from this member is greater than all the other Green River Members combined.
  • The Road Hollow Member – The oldest and thickest member representing Fossil Lake’s formation as it grew and deepened. 

Green River Formation – Layers 

While there are several layers within each member, there are two layers that are most productive; “18-inch bed” and the “sandwich bed.” The sediment deposits in this layer have records of life in shades of dull and dark, with bones of fish turning black and the scales remaining grey. 

On the other hand, the “sandwich bed” is around 6.6 feet thick and holds a record of near-shores species typically fossilized in the shades of orange and brown. 

When you look at the fossils from the two layers combined, you find evidence of various wildlife that has been uniquely persevered by nature. 

Green River Formation – How was it Formed?

Diplomystus_and_Knightia_Green_River Formation
Fossil Fish from the GRF of Colorado. Diplomystus and Knightia fossil fish. Photo: Wikipedia CC

A Biosphere of Nature

Interestingly enough, the following is a perfect example of the formation of how ecospheres materialize through the wonders of nature.

The evidence of life from the Eocene has its own story to tell from an era that began around 50 million years ago. Green River Formation fossils reflect a time when the landscape formation was complete and mountains and plains were separate. And since the streams of water were draining into the lakes, they carried large amounts of sand, mud, minerals and silt. Over time, as the sediments continued to fill in the lakes, it altered the lake waters’ chemical composition. As a result, it became the breeding ground for a variety of plant species. 

Enter Coal and Oil

Green_River_Formation_Oil_Gas_Fields_map
Green_River_Formation_Oil_Gas_Fields_map  (Wikipedia Public Domain) 

The climate of the Green River at that time was warm and moist, which further facilitated plant growth; creating a dense community of vegetation; subsequently providing a continuous supply of leaves, seeds and branches.

Plant debris in the lake was protected by the swamp’s water cover that continued to grow thicker over time. With immense pressure for millions of years, the plant debris has now transformed into coal. Moreover, as the blue-green algae continued to thrive in the lake, it spread over different parts and formed thick scum which eventually sank to the lake’s bottom. Over time, the algae-rich sediments transformed into the largest oil shale resource on the planet. 

Types of Fossils Found in the Green River Formation 

Green River Formation is home to fossils in a variety of shapes and sizes. You can find evidence of life in the form of intact fossilization (where the entire body of the species is intact), and you can also find fossils as fragments of a different part of the body. 

A possible explanation of this variation includes lake currents and the body’s state before fossilization and changing conditions within the lake system. 

A specific species that we can look into is fish. You can find evidence of fossils within the Green River lakes ranging from complete disintegration to fully intact skeletons. In some species, there is evidence of fossilization with food still inside the body of the species. The variety of fossils indicate the environment inside the lakes continued to change throughout the Eocene. 

What Makes Green River Formation Unique?

The Green River Formation fossils are one of the best-known sites for getting an insight into the Eocene. It gives exact information into what life was like millions of years ago. It contains evidence of hundreds of individual fish of different shapes and sizes. 

Additionally, fossil plants are abundant, including ferns, palm leaves and sycamore leaves, indicating the possible plant species along the lakesides. Fossils of various other species, including mammals, snakes, turtles, birds, bats, birds and crocodiles have also been found in the Green River Formation, depicting the possible variety of more advanced species in the region millions of years ago.

Given its wide variety of fossils, Green River Formation is one of the best-known sites for paleontologists worldwide. 

Geology

Understanding Rock Glaciers

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Rock Glacier
A rock glacier in the Chugach, Alaska mountains. Public Domain

Rock Glacier – Overview 

A rock glacier is a body of rock, mud, ice, snow, and water that rests on top of mountains. These sentiments head down towards the valley below due to the force of gravity.

Typically, rock glaciers are covered with debris on the topmost layer, cemented with snow and ice underneath.

If you look at the surface of these glaciers, you will find very little. At a glance, it may not even seem like a glacier. Once the ice below the glacier’s surface begins to move, the rocks on the surface adjust to the movement. As a result, ridges or flow features may appear on the glacier’s surface. 

Rock glaciers are typically small in size. One of the largest may be only a few feet thick but and a few miles long. The rocks on the surface are of varying sizes depending upon the source of supply. 

These geological wonders are one of the most spectacular natural phenomena on Earth. Let’s delve deeper and find out more about how they are formed and what are some of the different types of rock glaciers. 

Changes in Rock Glaciers 

Over time, rock glaciers may grow or shrink. Both the ice mass and rock mass can change depending upon several factors. 

The mass under the surface may change due to weather conditions. It can change due to heavy rainfall, avalanches, spring discharges, and local runoffs. Moreover, the heat and sunlight can cause the underlying snow and ice to melt, which eventually reduces ice mass and causes a downward movement of the glacier. These components can also be lost due to evaporation. 

On the other hand, the rock mass may grow due to talus (large rock fragments) from the mountain or the valley walls. It may also grow as a result of landslides. Rock mass decreases as the glacier is carried down the slope due to ice mass movements. 

Formation of Rock Glaciers 

These glacial mass formations can develop for a variety of reasons. Some of them result from the melting of ice covered with debris due to a landslide. Such glaciers are a common feature of steep-sided valleys where mountainous rocks respond to Earth’s gravitational pull. 

Types of Rock Glaciers 

Depending upon the activity, ice mass, and shape, these entities can be classified into several categories. Let’s look at each of the different types.

Based on the current activity level, rock glaciers can be classified into active, inactive, and fossil rock glaciers. 

Active Rock Glaciers 

Active glaciers contain a significant amount of ice and due to their large ice mass, they move down the slope at speeds ranging between a few inches/year to several feet/year. They typically have well-defined and prominent ridges and a steep frontal slope due to deforming ice. 

Inactive Rock Glaciers 

As the name suggests, inactive glaciers are passive, which means there is very limited downward movement. Such glaciers may still have ice, but the underlying ice mass is not deforming. As a result, there is virtually no activity. Apart from the movement, an additional difference is in the frontal slope. Since there is no movement, the frontal slope is gentler than an active rock glacier’s slope. 

Fossil Fuel Glaciers 

The third type is based on fossil rock glaciers. There is no underlying ice mass as all of the ice has already molten. Therefore, the top surface is often covered with vegetation, and the frontal slope is significantly less steep than the other two types. 

How rock glaciers are formed is another way to classify them. Typically the two classifications are:

Glacial 

This type was active glaciers at some point. They were either detached from their main body or melted due to weathering and other forces. Over time, the deforming ice was covered with talus from the mountains. However, a distinguishing feature is an average temperature that remained around 32F  (0℃) with limited precipitation. So the glacier, which was initially reliant on rain and snow now feeds on talus. And the underlying ice plays a role in the downward movement. 

Periglacial Rock 

Periglacial rock glaciers are formed as a result of the freezing and thawing of the underlying material. The talus that feeds the glacier underwent periglacial processes. The intense freezing and melting of snow at the core of the rock glacier accompanied by talus accumulation of the top results in the forming of a periglacial rock glacier. 

Classification According to the Shape – Tongue-Shaped Rock Glaciers and Lobate Rock Glaciers

Tongue-Shaped 

Tongue-shaped rock glaciers have a length-to-width ratio of more than 1, which means they have a greater length than width. Such glaciers are usually confined to narrow valleys. The rock mass supply (talus) comes from the steep and rocky highlands nearby. A prominent feature is that the rock mass is only added to the head of a tongue-shaped rock glacier resulting in vertical growth of rock mass.

Lobate 

Lobate glaciers have a length-to-width ratio of less than 1. Such ice masses have a greater width than length. The rock is often derived from the valley walls that enclose the glacier. Since it has a wider size, the rocks can join in the glacier from multiple sides, adding more to the glacier’s width. 

Rock glaciers that do not fall into the above two categories are called complex rock glaciers. 

Bottom Line 

Rock glaciers are an interesting geological feature that often appears as land masses and move downwards in response to gravity. While the gravitational pull is a significant factor, how the landmass moves depends upon several factors, with the deforming ice beneath the surface being the most prominent one. Weather conditions, how the rock glaciers were formed, and the source of rocks (talus) are also major determinants of the glacier’s movements. 

 

 

 

Geology

What are Fossil Fuels? A Brief Overview

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Did you know that fossil fuels do not only come from natural gas? Oil and coal are fossil fuels too, but what’s interesting is that they were all formed from extinct plants and animals that have decayed millions of years ago. Oh! If the dinosaurs really knew how much they meant to us!

These remains are referred to as organic matter and carbon is the element that is found in all organic matter. This is how we are able to determine what the compound is and how old it is. 

What Do Fossil Fuels Do for Us?

Times Square at NightJust look around. This is how we get our electricity, run our cars (cars that use combustion engines, not electric cars), provide power to our planes, and keep us warm in the winter. There are some caveats though. One is the impact they have on the environment. Another is that once the fuel is used, you cannot reuse it again. These are known as non-renewable resources, as compared to renewable resources like wind farms and solar energy. 

Crude oil, AKA petroleum or petro is a fossil fuel in liquid form. It is made of hydrocarbons, which is a chemical compounds of hydrogen and carbon. 

How Is Oil Extracted?
Oil RigAs mentioned, we know now that it is the remains of dinosaurs that is the oil that we use for energy and we know that this oil is found way beneath the earth, so in order to extract it, oil drills must be erected over the area.

It is not easy to find where the oil resides. Much testing must be conducted first. Sometimes it is found by accident. Remember the Beverly Hillbillies? 

Finding oil and gas trapped deep underground is very complicated and expensive, but the payoff is well worth it to the oil companies, and the landowners (mostly municipalities and countries) where their drilling takes place make a fortune. Just take a look at the Middle-Eastern Gulf states, but closer to home, there are Texas and California, as well as Alaska. Transporting the oil to refineries and on to international distributers was restricted until former President Trump opened up the pipelines, which helped advance the US economy and make America energy independent; however, to the chagrin of environmental supporters and the environment itself.

How are Oil and Gas Transported?

Oil drilling takes place on land and in the ocean. Once extracted, it is sent to the oil refineries since this fossil fuel contains lots of other compounds that need to be extracted so that the oil is pure. Large tanker ships, as well as pipelines, carry this oil to their respective refineries. 

Interestingly, there are more than 190,000 miles of pipelines in the continental United States and Alaska. They connect to other refineries and chemical plants which are then delivered to terminals where the refined product is trucked to consumers. 

What is Shale Gas?

Shale gas is natural gas that is found underground in shale rock. Fracking is the process used to extract shale gas. Profound openings are bored down into the shale rock. The gas is then siphoned into the boring gaps made by the drills which created cracks in the stone, empowering the gas to flow through the breaks into wells. From that point, it is funneled away for consumer use. 

What About the Environment?

Fossil fuels are known to be major pollutants.

Smokestack showing air pollution
Photo by Marcin Jozwiak on Unsplash

There are ongoing, contentious debates about which is currently more important, advancing the US economy or diminishing the oil transport and production so that the oceans and air can become cleaner. 

During the course of debates that are leading up to the US elections, Donald Trump believes that strengthening the US economy and energy independence is most important now, as well as being able to meet the growing energy needs across the world,  but Joe Biden feels that it is too dangerous to not take into account what effect the fossil fuel production and fracking is doing to this current environment and the dangers it could possibly have in future years. 

 

Geology

What Do Gemstones Tell Us?

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The ever-so elegant, breathtakingly beautiful and alluring gemstones used to accessorize outfits and adorn the human body do not just have a high monetary value, but also has to some an immutable mystical significance. It is true that people pay hefty amounts of money to possess jewels embellished with gems that were curated from the Earth’s center, but their worth is much more valuable for some. Whether the attributes associated with gemstones are accurate or not is a different debate altogether; nonetheless, the connection between the two cannot be denied.

Even if someone doesn’t believe in their symbolism and rebuffs all supposed properties assigned to material things, it wouldn’t change the fact that gemstones have been regarded as sacred objects for centuries. Keeping that in mind, we are here to discuss the meaning given to gems without questioning the rationale behind them. So, without further ado, let’s dive into gemstone symbolism.

Here is a list of legends and the resulting mythical narratives given to some of the most popular gemstones.

Ruby

This crimson beauty is one of the most enthralling natural stones and is known for its color and hardness. Due to its color, many civilizations in the past believed it to hold the power of life.

Ancient Hindus would present ruby to their God Krishna as they believed doing so would make them emperors in the next life. Christians also hold the ruby dear because it’s mentioned in the Bible four times that it represents beauty and wisdom.

Ruby, which comes from the Sanskrit word Ratnaraj, meaning king of precious stones, was considered lucky in many cultures, especially among European royalties and upper class of the medieval times. The ancient elite in Europe would collect ruby stones because it was believed that having one guarantees wealth, wisdom, success in love and good health.

In sum, the ruby is known to signify vitality, prosperity and royalty.

Lapis

Lapis Lazuli is among the gems that are associated with deities and royalties. It is because of this association that we got the distinctive color categorization ‘royal blue.’

Egyptians believed that Lapis came from the heavens and provided protection in the afterlife, which is why they kept the stone in their graves and used it to make statues of their gods, totemic objects and burial masks.

Egyptians were not the only ones to regard Lapis as a gemstone that provides safety in the afterlife; many cultures in Asia, Africa and Europe also believed so and would bury it with the dead.

During the time of Renaissance, painters used Lapis to produce ultramarine pigment for their paintings by crushing the stone to dust so as to add a touch of reality.

Lapis is a stone that is supposed to bring enlightenment and awareness. In other words, possessing a lapis lazuli stone gives wisdom and the ability to see and understand the truth.

Emerald

The Emerald is one of the many stones given to King Solomon by God or so narrated by legend. It was a gift to the king that endowed him with power over all creation. The Incas, people of the Inca Empire of Pre-Columbian America, used it to make jewelry and conduct religious ceremonies. However, the Spanish would trade it for other more valuable stones such as gold.  

The Emerald is supposed to grant psychic powers to the wearer; some ancient civilizations believed that keeping it under the tongue would reveal the truth and show the future. Now, however, the emerald is associated with peace and balance. People think that it provides inner peace and relieves stress. A factor behind this idea could be the color of the stone. Since the color green symbolizes harmony, growth and emotional well-being; hence, the emerald stone is also assigned similar properties. 

Not a bad idea if it works, noting the turmoil we are subjected to at this time.

Amber

Although amber is not an earthy stone and is actually fossilized tree resin, it is still recognized as a gem. In the mythology of the Northern German people, called the Norse folklore, Freyr, the God of fertility’s tears would turn into gold and amber stones when she cried because her husband was away.

Furthermore, amber is associated with light and electricity and is believed to result from the concealment of sunlight. If only Edison knew! Because of this connection to the sun, amber carries the reputation of being a nurturing, warm stone used to provide comfort to the ill.  

In the time of ancient Greeks, this yellowish stone was highly regarded as it was sacred to the Greek God of Apollo. Lastly, the Chinese once believed that amber is the soul of a dead tiger transformed into the rocky shape of the sunny gem.

Topaz

Early gem experts regarded topaz as a stone that was capable of protecting against diseases, untimely death, strengthening the intellect, lessening sadness and anger and eliminating cowardice. It was also believed that topaz could cool down boiling water and emit light. 

Legend has it that the mystic Roman Catholic Saint of Hildegard of Bingen claimed that she read prayers in a darkened church with the light emitted from a topaz stone.

Since topaz has long been associated with creating light and reducing negativity, it is believed to provide mental clarity, positivity and the ability to focus on the wearer.   

Garnet

Garnet is also one of the stones gifted to King Solomon by God. It was also used by Prophet Noah to light up his ark; hence it is associated with the removal of darkness and imbuement of life, passion and love.

Garnet is considered a totem that brings good luck and eliminates dangers and distress. It is given to travelers for a safe return or people trying their hand at business as it is supposed to bring good fortune. It is also known for removing emotional distress between lovers, especially if caused due to distance.

Although these are only a few of the gemstones with the meanings behind them, there are many more, but these are enough to give you an idea of the legendary and mystical significance gems carry. With that said, it’s possible that all the stories regarding gems aren’t real, but many people worldwide believe in them (possibly psychologically) benefit from their unfaltering belief. But whether these legends are true or false, why would it matter if people do feel better when they are in their possession? 

Geology

Where Do Gems Come From? Summarizing the Million-Year Process

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A rock with gemstones
Photo: Unsplash.com

If you’ve ever had an opportunity to see a gemstone in its raw form, you probably wouldn’t be able to guess how valuable they can be once refined. Gemstones don’t form just like that; it takes thousands to millions of years. It’s their rarity and the tough process of extraction that makes them such a valuable commodity!

While most people are fond of gemstone jewelry, gem collectors are more interested in knowing where they come from. If you’re among the latter, you may be interested to know how the breathtakingly-beautiful ruby gets formed or how the sparkling sapphire came into existence. If so, you’ve come to the right place. This blog post summarizes the million-year process of gem formation. Let’s hop into the topic without any further delay.

The Origin of Gemstones 

Simply put, gemstones come from rocks. Rocks are made from an assortment of different minerals. The most common minerals that are most abundant in rocks include silicates like mica, olivine, quartz, emeralds, oxides, carbonates, halides and sulfides. Many minerals come together to form beautiful and unique crystals and out of these crystals, gemstones are the most valuable. Gems look quite ordinary in their raw, uncut form, but once they are extracted, cut and polished, the luster and brilliance are just incomparable!  

How Are Gemstones Formed?

Most gemstones are formed inside the earth’s crust, which is the top-most layer. They’re usually created at a depth of 3-25 miles. However, some gemstones from deeper down in the mantle. These include peridot and diamonds. The mantle mostly consists of magma, which is molten rock.

Since most of the gemstones form in the earth’s crust, let’s look at the crust a bit in detail. The crust comprises three different kinds of rocks; igneous rocks, metamorphic rocks and sedimentary rocks. They differ in the way they’re formed. Some gemstone varieties may be formed from any one type of rock, while others may be associated with multiple rock types. 

Igneous Gemstones

The igneous rocks are formed by the solidification of magma that rises to the crust from the mantle through volcanic pipes. Once it reaches the surface, it’s exposed to a contrastingly lower temperature, and as a result, it solidifies. However, if the process of solidification is slow and gradual, it can crystallize to form minerals. Some of the gemstones that are formed through the igneous process include quartz (ametrine, amethyst, etc.), garnet, apatite, moonstone, aquamarine, topaz, tourmaline and zircon.

Sedimentary Gemstones

After the igneous rocks reach the earth’s surface, they’re exposed to weathering and erosion, causing them to deteriorate into smaller particles. These smaller particles are moved by water and wind and with time, the layers of these smaller sediments build up underwater or on land. As the sedimentation continues, the pressure by the upper layers results in the layers below to become compressed and compact. They also undergo numerous physical and chemical changes that eventually lead to the formation of sedimentary rocks. Gem formation that occurs through sedimentation results in the formation of sedimentary gemstones that include opal, jasper and malachite.

Metamorphic Gemstones

Some processes put the minerals of igneous rocks and sedimentary rocks under immense pressure and heat that brings about a change in their structure and chemistry. These processes include contact metamorphism and regional metamorphism. As a result of excessive heat and pressure, igneous and sedimentary rocks are converted into metamorphic rock. The gemstones that are formed as a result of metamorphosis include turquoise, ruby, jade, zircon, sapphire, etc.

The rocks are constantly changing. And all of this doesn’t occur overnight. It takes millions of years. It took your favorite ruby that you so fondly wear around your neck at least several thousands of years to be what it is today.

What Makes Gemstones So Precious?

Gemstones aren’t waiting on the earth’s surface where you can pick them up like you pluck a flower or a seashell. They’re embedded in rocks, such that you can’t even tell if a particular piece of rock has gems in it. They are difficult to locate and extract. As the saying goes – best things don’t come easy and that sits fit in the case of gemstones! 

Even after gemstones are extracted from the rocks, it takes a lot of effort to bring them into a shape that is lustrous and attractive. You wouldn’t want to wear a pendant with an unrefined piece of rock around your neck, would you? It’s the shine, color and luster that make gemstones so highly attractive. 

Gem formation takes millions of years. Assuming that all the gemstones present today are extracted from the earth, we won’t have any new supply of gems for the next thousands of years. The million-year process of gemstone formation is one of the reasons why gemstones are so precious. 

All minerals are precious, some more than others. The value of gems depends on how common or rare they are. The more widely a gemstone is available, the less expensive it’ll be. They’re divided into different categories; precious, semi-precious and organic. Precious gemstones include ruby, sapphire, diamond, and emerald. Semi-precious gemstones include opal, topaz, jade, and others. Organic ones include pearl, coral, and amber. 

Closing Word 

Now you know where gems come from – they come from rocks! The type and quality of a mineral depend on the type of rock it comes from. While all gems are precious, the varying mineral composition gives them a characteristic color and appearance.

Gemstones are widely used in jewelry. A lot of people are involved in gem trading. And many people simply love to collect them. Knowing that a gemstone goes through multiple stresses over tens and thousands of years before taking the form we see today, there is no doubt that people consider them as highly precious assets! 

Geology

Planet Earth is a Lot More than You Could Imagine

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View of the Earth

How old do you think the Earth is? Never mind, we’ll tell you. It’s almost 4.54 billion years old!

Let that sink in. The planet may be old but it has all the ingredients to make your jaws drop and eyes pop! How else would you describe the mighty volcanoes, drifting plates, oceanic abysses, and meteor crashes?

Even with geologists and scientists constantly being on the hunt for new discoveries, there is so much about the planet that is yet to be discovered. In this post, we will give you the smallest gems from our planet’s treasure trove.

And the Rocks Walk

Don’t believe us? Take a trip down to the Death Valley. There at the Racetrack Playa (a pancake-flat lakebed) and the rocks walk. In times when there are storms, there are instances where rocks weighing tens and hundreds of pounds can move down a distance. When there’s no storm, there’s a nice wind that gives the rocks the kick start they need.

Where’s the Longest Chain of Mountains

Mountains in Colorado Springs
Mountains in Central Colorado

If you’re thinking it’s the Andes, you’re wrong. To locate the largest range of mountains on the planet, you’d have to take a swim into the ocean. The Mid-Ocean Range stretches across a distance of 65,000 km on the seabed. Compare the Andes’ 7,000 km stretch to that!

This chain of volcanic mountains maintains an average height of 18,000 feet above the sea bed. But here’s the most fascinating fact: This mountain range is not stopping! As volcanoes erupt, they create sufficient crust to add more underwater mountains to the already global mountain range.

Ever Heard of the Exploding Lakes?

They do exist! The kivu, Nyos and Monoun Lakes in Cameroon and on the Congo-Rwanda border actually explode. These deadly crater lakes are situated above volcanic Earth. The magma beneath the releases gusts of carbon dioxide into the lake water. This creates a deep layer rich in carbon dioxide right above the lake beds. This carbon dioxide at times explodes, and is fatal enough to suffocate a passerby to death.  

Lake Nyos (Wikipedia)

Where Giants Breathe

No we’re not talking about the Yetis or the Bigfoot! The next things that come to mind when we think about giant life are elephants and whales. But could you think of a tree being larger than these creatures? The General Sherman is a giant sequoia that stands at 311 feet tall (A blue whale roughly grows to a 105 feet long) with the largest known stem volume on Earth. The General Sherman’s trunk measures a tad bit more than 52,500 cubic feet. That is colossal!

Did you know that there are actually spots on Earth where no precipitation has been recorded – EVER!

The center of the Atacama Desert in Peru and Chile has seen no rain whatsoever. It is known as the driest place on the planet. That’s not all. The orb we inhabit is constantly evolving, there’s always a new surprise about the Earth popping up every now and then. Take the time to imagine the extent of things we’re yet to discover about the fascinating planet we live in!