G6- The Grand Canyon: A Window to Earth’s History 800-900L -02

Introduction

Every year, nearly 5 million people come to see the Grand Canyon. They are amazed by the sheer scale and beauty of the canyon. While tourists come mostly for the spectacular views, scientists also visit the Grand Canyon. Unlike tourists, they come for other reasons. For the scientists, the Grand Canyon is a window into Earth’s past.

Some scientists come to study particular rock strata. These scientists hope to better understand what the Earth was like at specific time periods. Other scientists are still attempting to learn more about how the Grand Canyon’s was formed.

The Grand Canyon is part of the Colorado River Valley. For scientists, it is a veritable playground. The canyons has nearly 40 exposed sedimentary rock layers. These exposed layers allow the scientists to study rocks. Some of these rocks date back 2 billion years. By studying these rock layers, scientists are able to construct a storyline of past events. You may wonder how it is possible to know what happened so long ago. Just like a detective, a geologist, a type of scientist who studies rocks, is looking for clues.

Age of Sediments and the Law of Uniformitarianism

James Hutton, also known as the ‘Father of Modern Geology’ had set forth a critical principle. This principle is what guides geologists in their work today. It was Hutton’s principle of uniformitarianism that established Geology as a proper science. His proposed that to understand the past, you must understand the present. To understand how the Grand Canyon was formed, you must first understand the current process of erosion and sedimentation. He believed that the processes that are now in place have always been in place. It is this principle of uniformitarianism that is the backbone of modern Geology. So how can knowing about the present help us learn about the past?