The first article on the geology of the Grand Canyon, where a series of events led to the emergence of the canyon. It began with the formation of the inner gorge’s metamorphic and igneous rocks two billion years ago, which were uplifted between 70 and 30 million years ago due to tectonic shifts. Subsequently, the Colorado River started to erode and carve the plateau, gradually widening the pathway and creating the canyon, and it began 5-6 million years ago (National Park Service par. 3). There is one main reason why the canyon is large as it is today. It is due to the fact that the Colorado River has been eroding and carving the plateau for almost six million years, which is a substantial amount of time to create the given landscape.
The entire process of the canyon formation is called downcutting, which refers to a river’s continuous erosion of the rock mass. The sheer scale of the down-cutting is directly dependent on a number of characteristics of the river, such as flow, volume, and slope (National Park Service par. 20). The river itself participates in the deposition of the rocks, which means that there are two categories of rocks. The first group is comprised of rock deposits older than the river, and the second group consists of rocks younger than the river because the latter is the main cause. An interesting fact about this can be found in the Spillover Theory, which claims that “the ancestral Colorado River was temporarily dammed behind the Kaibab Plateau and other high points” (National Park Service par. 44). In other words, the blockade of the stream of the river can be a reason for the active down cutting since a higher volume river was subsequently released.
The second article focuses on essential and interesting concepts centered around the Grand Canyon. This UNESCO World Heritage Site is reflective of the geological history of the landscape. Stratigraphy allows experts to be able to observe and analyze the layering patterns of the rock in order to describe the planet’s state, including climate, during the specified period of time (Geology and Ecology of National Parks par. 3). There are three primary layers of rocks, which include Paleozoic strata, the Precambrian Grand Canyon supergroup, and metamorphic basement rocks. In some cases, there is a missing layer within the rock formations, which are called unconformities, such as the Great Unconformity of the Grand Canyon (Geology and Ecology of National Parks par. 4). These gaps also provide invaluable insight into the history of layering since it means that the missing layers eroded before the deposition.
It should be noted that there are three major types of rocks such as metamorphic, sedimentary, and igneous. The latter is the oldest rock formed due to the cooling of the magma or lava, and the former is the result of two other rocks exposed to pressure and heat. Sedimentary rocks form due to the sedimentation of sand and mud. Geological insight is further enhanced by fossils, such as brachiopods, burrows, tracks, and trilobites, each of which represents living creatures of the past (Geology and Ecology of National Parks par. 5). The most interesting fact is that the canyon is much younger than the rock deposited in the terrain because the Colorado River became the driver of erosion relatively recently.
Works Cited
Geology and Ecology of National Parks. ” Grand Canyon Geology.” USGS.
National Park Service. ” Geology.” NPS.gov.