Relative dating exercise 1
Shown below is a real transect across the entire Grand Canyon (in two parts).This profile is composed of both the surface topography and the inferred geology underfoot.Applying the principles of relative dating to these rock exposures (also called "outcrops"), we can reconstruct the sequence of events that created the geologic features which we see.Events can be the deposition of a sedimentary layer, the eruption of a lava flow, the intrusion of magma to form a batholith, a fault (break) in the rock that shifts one side relative to the other side (and causes an earthquake), a fold that bends and distorts rock layers, or any number of other geologic processes.
As geologists piece together the information at various outcrops, they can begin to assemble a "geologic map" (like a road map) of an entire region (consisting of many square miles).We will learn more about this method of identifying rock units and geologic time periods in next week's lab.Question 5: On the South Half, approximately how high is Hopi Point on the Coconino Plateau? Use the letter labels to refer to the distinct rock layers.What is the approximate elevation of the Colorado River (shown by the arrow pointing downwards)? Question 6: On the South Half, which rock unit is likely to be the youngest (most recent)? Question 7: On the South Half, we can also notice that many faults have occurred in the area of the Cheops Pyramid.These are the dark lines that slice through the rock formations.