Welcome to Red Mountain Open Space. If you haven't been here before, you may not know that you are standing in an area that took millions of years to create. Let me explain.
When you dissect something in biology class, you cut it into pieces and looked at all of the parts. When land is dissected, it is “cut by irregular valleys and hills". If you look at the map below, you can see that much of this area is cut up by different streams and rivers.These happened over millions of years. The question is how did it happen?
Erosion
Erosion is the name for the processes that both break down rocks (weathering) and carry away the breakdown products (transportation). As a general rule, if rock is just broken down through mechanical or chemical means, then weathering has occurred. If that broken-down material gets moved at all by water, wind or ice, then erosion has occurred.
Erosion is different from mass wasting, which refers to the downslope movement of rocks, dirt, and regolith primarily through gravity. Examples of mass wasting are landslides, rockfalls, slumps, and soil creep.
Erosion, mass wasting, and weathering are classified as separate actions and often discussed individually. In reality, they are overlapping processes that usually act together.
The physical processes of erosion are called corrasion or mechanical erosion, while the chemical processes are called corrosion or chemical erosion. Many examples of erosion include both corrasion and corrosion.
Agents of Erosion
The agents of erosion are ice, water, waves, and wind. As with any natural process that takes place on the Earth's surface, gravity plays a major role as well.
Water is perhaps the most important (or at least most visible) agent of erosion. Raindrops strike the surface of the Earth with enough force to break apart soil in a process known as splash erosion. Sheet erosion occurs as water collects on the surface and moves toward small streams and rivulets, removing a widespread, thin layer of soil along the way.
Gully and rill erosion occurs as runoff becomes concentrated enough to remove and transport larger amounts of soil. Streams, depending on their size and speed, can erode away banks and bedrock and transport large pieces of sediment.
Glaciers erode through abrasion and plucking. Abrasion occurs as rocks and debris become embedded on the bottom and sides of a glacier. As the glacier moves, the rocks scour and scratch the surface of the Earth.
Plucking takes place when meltwater enters cracks in the rock beneath a glacier. The water refreezes and breaks off large pieces of rock, which are then transported by glacial movement. U-shaped valleys and moraines are visible reminders of the awesome erosive (and depositional) power of glaciers.
Waves cause erosion by cutting away at the shore. This process creates remarkable landforms like wave-cut platforms, sea arches, sea stacks, and chimneys. Due to the constant battering of wave energy, these landforms are usually short-lived.
Wind affects the surface of the Earth through deflation and abrasion. Deflation refers to the removal and transport of fine-grained sediment from the wind's turbulent flow. As the sediment is airborne, it may grind and wear away surfaces with which it comes in contact. Like with glacial erosion, this process is known as abrasion. Wind erosion is most common in flat, arid areas with loose, sandy soils.
To get credit for this EarthCache, send the answers to the following questions.
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What role did erosion play in separating the two landforms you see on either side of you?
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Do you believe the two structures were combined in the past?
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What types of sediment and rocks do you see on each side of GZ? (Describe the soil profile: color, texture, size of particles)
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Take a photo of yourself or a proxy at or near GZ. (Required)4
Resources
- Dictionary.com
- Larimer. “Red Mountain Open Space (Natural Resources).” Larimer County, 2020, www.larimer.org/naturalresources/parks/red-mountain.
- Alden, Andrew. (2020, February 11). What Is Erosion and How Does It Shape the Earth's Surface? Retrieved from https://www.thoughtco.com/what-is-erosion-1440855
- Geocaching.com Guidelines - EarthCache Logging Tasks