Climate and geography combine to influence Scotts Bluff National Monument through weathering erosion and deposition processes – part of what is known as the rock cycle.
Weathering occurs as a result of physical processes, including temperature variations, freeze-thaw cycles, water, wind, and living things interacting together to gradually break down surfaces over thousands or millions of years.
Weathering, also known as degradation or disintegration of rocks and minerals on Earth’s surface, can take place physically, chemically, biologically and other forms. Biological weathering occurs when animals, plants or their roots interact with rocks and minerals directly whereas erosion refers to movement of rock particles by wind, water or gravity and must occur between distinct places on the planet’s surface.
The Grand Canyon is an example of natural phenomena shaped by weathering and erosion, specifically through weathered sediment. Sediment can consist of sand, clay, small pieces of rock or even human bone fragments and plant remains; all forms of weathering and erosion continue their work over time as landscapes gradually change over time.
Physical weathering occurs when temperature variations cause rocks to wear down or disintegrate over time. For instance, when water seeps into cracks in rocks and freezes into solid block of ice that expands and breaks apart the rock face – known as exfoliation in weather science terms – physical weathering begins. Changes in pressure can also have an effect on weathering; this is known as unloading; once overlying materials have been cleared away exposing underlying rock, which begins expanding and cracking which causes sheeting (known by other names in technical jargon).
Weathering wears away at rocks and minerals, causing erosion. Erosion is the natural process by which these materials travel to another place where they eventually fall to their end destination; always downward in direction caused by forces related to weathering.
Water is the main cause of erosion. Raindrops can erode soil as they hit surfaces, while flowing waters carry away material as they move down streams or rivers. Wind can also act as an erosional agent by carrying dust, sand and particles from one location to another and shaping rock surfaces into smooth forms such as Arches National Park’s Arches formation or towering dunes of Badain Jaran desert.
Physical (mechanical) erosion is a type of erosion that changes the shape and size of rocks without altering their chemical composition, and often contributes to landslides or mass wasting events. Physical erosion also has human influences such as deforestation, road building and industrial agriculture that contributes to its rapid progression; climate variables (including rainfall intensity, length, seasonal temperature ranges and seasonality), as well as climate, seasonal changes, vegetation coverage and its ability to hold soil together through roots can limit sediment runoff into rivers.
Weathering, erosion and deposition are natural processes that reshape Earth’s rocky terrain. No rock or mineral can withstand their forces: weathering is the breaking down of rocks, minerals and soil; erosion transports that broken material away; deposition is when these particles settle onto beaches (ie river sediment).
Time of Exposure of Rocks as Predictors of Weathering and Erosion | Lava rock is far less vulnerable to weathering and erosion than rocks exposed for longer.
Weathering can be caused by water, salts, acids, ice, plants and animals alike. Rabbits digging in cracks in rocks over time makes the crack bigger which eventually fractures it; similarly leaking water through cracks freezing then melting can break apart the rock as well.
Every sedimentary rock on Earth is the result of weathering, erosion and deposition processes. Erosion involves the breakdown of rocks, minerals and soil which is then transported by wind, water or glacial ice for transporting. Once their energy source has depleted their momentum the particles from this transport cease being moved further until eventually becoming deposited ie rivers deposit sediment onto their beds or winds deposit sand onto beaches.