Sandstone formations weathering into soil are part of the rock cycle.
The concept of the rock cycle is one of the basic foundations of historical geology. It's a general model describing how rocks and minerals change and recycle. It explains and ties together the diverse processes of rock formation, weathering, erosion, volcanism, plate tectonic folding, faulting, and subduction. In a nutshell: molten magma hardens and solidifies into igneous rock which uplifts into mountains, is eroded into dirt that eventually forms sedimentary rock which metamorphosizes back into igneous rock, restarting the cycle.
Appalachian Mountains
When young mountains are first uplifted by tectonic plate collisions, they are tall and jagged, like the Rocky Mountains. Over millions of years old mountain ranges like the Appalachians are worn down by the effects of wind, water and the freezing and thawing cycle. Their peaks become low and rounded as the rock they are made up crumbles into dirt and sand. This sediment is transported by wind and water until it's deposited into layers that eventually become sandstone, shale or other types of sedimentary rock. As the rock cycle progresses, this rock too will become eroded into soil.
Glaciers
Glaciers are a key part of the rock cycle. As mountains are pushed up, glaciers erode them back down again. During the ice age glacial periods, giant sheets of ice ground rocks up into the fertile glacial till soil covering the American Midwest. The glaciers moved granite boulders and rocks from Canada and dropped them throughout the Midwest until they far outnumbered the native sedimentary rocks. The many lakes and rivers carved by the glaciers allowed for more water erosion and transport of sediment, continuing the never ending rock cycle.
Grand Canyon
The rock cycle and the water cycle are inextricably intertwined, one affecting the other. The formation of the Grand Canyon illustrates the relationship of uplifting and erosion. The Colorado Plateau was uplifted into a mountain range by a combination of tectonic continental drift and volcanism. The mountains eroded away and their sediments were deposited on the bottom of an ancient ocean, forming the many layers of sedimentary rock visible in the canyon walls. According to John Douglass, the ancient Lake Bidahochi burst its natural dam walls, releasing the spillover rush of water that cut through the soft rock and carved out the giant canyon in 5.5 million years.
Tags: rock cycle, sedimentary rock, eroded into, Grand Canyon, igneous rock, into dirt, into igneous
