Final answer:
The relationship between the age of rock layers and depth in the Grand Canyon follows the principle of superposition, with the oldest rocks at the bottom and the youngest on top, demonstrated by the Great Unconformity and other geological features in the canyon's stratigraphy.
Step-by-step explanation:
The relationship between the age of rock layers and the depth traveled into the Grand Canyon can be explained by the principle of superposition and other sedimentary processes. In the Grand Canyon, this relationship is observed because the oldest rock layers, dating back over a billion years, are found at the deepest points in the canyon, whereas younger rock layers are successively stacked above.
The Grand Canyon's stratigraphy reveals a geological history that includes sedimentary, igneous, and metamorphic rocks, with the ages of these rocks decreasing from bottom to top. The Great Unconformity within the canyon exemplifies a significant gap in geological time, and rock layers above and below this unconformity are vastly different in age.
Scientists have deduced the canyon's geologic history by studying critical features such as the types of rocks present, the various rock formations, and the locations where faults and folds are evident. These elements help support hypotheses about the canyon's formation, whether it started to form 5 million or 70 million years ago. The settling and layering of sediments, followed by their compaction and cementation, created the sedimentary rocks that are widely visible in the canyon.
The Grand Canyon is a natural record of nearly 2 billion years of the Earth's history. It also provides evidence for geologic processes like erosion and tectonics that shaped the landscape we see today. Given the continual erosion by the Colorado River and the ongoing active tectonics, the geological story of the Grand Canyon is still unfolding.