A fascinating phenomenon that occurs in nature is the process of frost heaving. When soil is exposed to freezing temperatures, it can be observed that the soil rises to the surface.
This happens due to the shrinking of soil particles as they are cooled by freezing water. This phenomenon is most noticeable in urban areas with concrete and asphalt roads.
When a snowstorm passes over a road, it can be observed that the snow on top of the road has increased in height. This is due to the frost heaving occurring beneath the road.
This phenomenon has been studied and applied in engineering projects such as highways and runways. Engineers must take into consideration how much ground will rise due to frost heaving, or their project will have structural issues later on.
This is how you get rock salt
A beautiful and useful result of this process is rock salt, also known as halite. Rock salt is a mineral composed of sodium chloride, or NaCl.
As the water freezes in the cracks of the rock, it separates the water molecules into sodium and chloride ions. These then combine to form crystals of halite, also known as salt.
The sea water floods the caverns beneath the earth’s surface and then drains away, leaving behind masses of salt. This is why there are deposits of rock salt in certain places around the world.
Sea water is very salty, so when it freezes, it does so with a lot of space between the molecules. This helps to prevent it from bonding together into a solid block of ice like freshwater does.
Because of this, when sea water freezes, it does so in thin sheets that break off easily when exposed to heat or pressure.
Helps break down rocks
As we mentioned earlier, saltwater surfers use tide pools as a way to find good surfing spots. The same can be said for marine biologists, who use them to study animals and ecosystems.
Tide pools are natural pools of water that form when waves crash against the shore. These pools are surrounded by rock, which forms a crack where water can be trapped.
Marine life, like anemones and coral, live in these tide pools. This is due to the nutrients in the water and the sunlight that filters into the pool.
How does this connection relate to breaking down rocks? Well, as tides go in and out, saltwater floods these pools. Then, when the tide goes out, there is less water in the pool, so some of the rock surface is exposed.
Over time, this exposure wears down the rock a little bit more until it breaks down completely.
Rocks are composed of minerals
A mineral is a naturally occurring material that is made up of a chemical compound and has a specific chemical makeup. There are over 5,000 known minerals, and they come in many different types.
Some examples of minerals include quartz, calcite, and feldspar. All of these minerals are found in ice glaciers, and they help scientists understand how these glacial formations change over time.
Glaciers are huge masses of ice that flow down from the polar regions toward the sea. As the ice moves down the mountain, it picks up bits of rock that get embedded in the glacier. When the glacier melts, these rocks are left behind as sedimentary deposits.
Scientists have been finding strange formations in these sedimentary deposits that look like broken glass. They believe that this glassy structure comes from water seeping into the cracks of the rocks and freezing.
Water breaks down minerals
Water has a unique quality that allows it to break down minerals and rocks. This quality is called frost fever, coined by Dr. Kenneth Winham.
Frost fever is the ability of water in frozen form to chip away at solid surfaces. This happens because of the repeated freezing and thawing of water in the soil.
Water seeps into the soil and freezes, then thaws and freezes again. This process repeats until winter ends and warmer temperatures occur. When the water in the soil freezes, it pushes against the surrounding soil and rock, chipping it away bit by bit.
This process is very slow, but continuous.
Break down enough rocks and you can collect the resulting sand
When water freezes in the cracks of a rock, it creates a kind of glue that helps to hold the rock together. This is because of the way ice crystals form when the water freezes.
Water freezes by separating its liquid molecules into hydrogen and oxygen atoms and then linking these atoms into a lattice-like structure called a crystal.
The lattice forms directions, called directions, and this structure helps to hold the water molecule grouping together.
When the water freezes in rocks, part of this crystal forms right on top of the rock itself, helping to hold it together. This is why breaking up rocks with ice in them is harder than breaking up rocks that are dry.
Thick layers of ice on top of rocks can also help break down those rocks by weighing them down.
Understanding this process can help you understand the breakdown of other substances as well
When water freezes in the micro fractures of a rock, it forms ice crystals. As these crystals grow and expand, they put pressure on the surrounding rock. This pressure contributes to the disintegration of the rock.
As the ice melts, it leaves behind holes called cavities. These cavities also help break down the rock as they get bigger or smaller depending on the temperature fluctuations.
When temperatures drop, more ice forms and increases cavity size. When temperatures rise, the ice melts and reduces cavity size. This cycling process perpetuates further rock breakdown.
By now you’re probably wondering what role bacterium plays in this process. Well, some bacteria are able to survive in freezing conditions by forming a protective cell membrane shell called a biofilm. Biofilms can be found on rocks submerged in water for long periods of time.
Do this experiment at home!
Try freezing water in different mediums to see how it affects the ice. You can freeze water in plastic, glass, or foam containers, on plates or trays, or in other natural materials like tree branches or stones.
Freezing water in plastic, glass, or foam containers will result in very thin ice because of the material of the container. The thicker the container, the thicker the ice will be.
Freezing water on a plate or tray will result in very thin ice because of the surface area of the ice. The thicker the plate or tray, the thicker the ice will be.
Placing water in natural materials like trees and stones will result in very interesting shapes of ice! Be careful when removing these to avoid breaking them.
Get a rock with cracks in it
You can find rocks with cracks in them almost anywhere. Most of the time, you can simply pick up off the ground where they naturally occur. Other times, you will have to search a little harder to find a decent sized rock with cracks in it.
Surprisingly, many hardware stores sell smooth river rocks that have interesting patterns and coloration. These are great for starting your ice cube experiment!
You can also buy specialized concrete forming blocks that have very defined horizontal and vertical grooves in them. These are perfect for creating an ice cube experiment that shows the structure of the block.
Once you have your rock, set it somewhere where it will not be disturbed until it is ready to be used.