Answer to Question 1
According to the text, about 200 million years ago, tectonic forces began moving the North American Plate westwards, it eventually collided with the Pacific Plate, and the force of the collision, called the Columbia Orogeny, moved east over North America, cracking enormous masses of rock and forcing the sedimentary layers up and over the adjacent land.
This process created the main ranges of the western and central Rocky Mountains.
A second collision, known as the Laramide Orogeny that ended about 35 to 55 million years ago, created the foothills and the front ranges of the Rocky Mountains. This was also a time of volcanic activity in the Rocky Mountains, but eventually the volcanic activity ceased and the magma cooled, leaving craterlike formations called calderas. In the millennia that followed, water flow carried sediment from high in the mountains into the valleys and plains below, creating v-shaped valleys like Hell's canyon at 7800 feet, which was shaped by the Snake River.
Many of the features of the mountainous west were created by glaciation. Glaciers reached as far south as the Rockies of New Mexico. When the glaciers receded, they carved magnificent u-shaped valleys that are much wider than the v-shaped valleys carved by water.
Answer to Question 2
The invention of the steel plow in the 1840s allowed farmers to plow heavy prairie soils that previously were unfarmable. Windmills have the potential to provide millions of dollars to farmers and rural landowners.
Posterior view of the Heart, outlining the major arteries
This chart illustrates the “drip down” model of government. In this, politics is formed by the soc
Major parts of the cell and the structures located inside the cell.
Major Wind Systems: Monsoons
Vertebral column. Avoid heavy pressure directly over spinous processes.
Maternal age is the major risk factor for autosomal trisomies of all types. By age 42, about one in