Plate Tectonics and the Alamo Impact
North America Placement
The Earth’s landmasses are more dynamic than one may think. The outer layer of the Earth’s crust is actually broken into a series of tectonic plates that move independently from one another. The movements of these plates are responsible for building the Earth’s tallest mountains and deepest trenches.
As these plates moved through geologic time, so did the continental landmasses atop them. Different movements through Earth’s history have altered the shape, size, and location of our continents. During the Devonian Period, early North America was situated around the equator. This location brought about a warmer and wetter climate, and was especially superb for marine, reef-building organisms.
Nevada Placement: Was there a Nevada?
The Nevada landscape we know today is very different from the one that existed in the Devonian Period. In fact, almost all of Nevada was completely underwater during this time. The landmasses that make up the state of California did not yet exist, making the Devonian coastline further east than its current position. For this reason, much of the rock deposited throughout Nevada during this time was limestone, a sedimentary rock largely composed from skeletal fragments of marine organisms.
Subduction Zones: How do they work?
As stated previously, the Earth’s outer layer is comprised of several tectonic plates that move independently. Often times, one tectonic plate will move and collide with another. When this occurs, one of the plates will subduct under the other, or be pushed beneath the other plate. This event creates what is known as a subduction zone. As the underlying plate is pushed even further beneath the overlying plate, it begins to heat up and partially melt. Much of this molten rock can rise up through the overlying plate and create a series of volcanoes.