How is relative dating used to evaluate geologic time
Geologists attempt to unravel geologic history by studying the geometry of outcrops in an area.
Why do landscapes in different areas have unique characteristics? Landscapes change from one region to the next because of the composition and character of bedrock changes from place to place.
(See section 1.10 in Chapter 1 for a discussion on geologic time.) Bedrock is the solid rock that occurs beneath soil or alluvium (unconsolidated sediments) that coved the surface of the land in most locations.
In some places the bedrock is exposed as rocky outcrops scattered across the landscape, particularly in mountainous areas or along stream canyons.
Igneous rocks includes intrusive rocks (rocks that cooled below the surface) and volcanic rocks formed on the Earth's surface by volcanism.
Igneous rocks also form from melting associated with extraterrestrial impacts.
The logical place to start discussion is to examine the material below our feet.