Answer to Question 1
Answer: The principle of superposition states that when rocks form at Earth's surface in layers, the lowest layer formed first and each successively higher layer is younger than the one below. The principle of original horizontality states that sedimentary layers are horizontal, or nearly so, when they are deposited. Non-horizontal layering indicates disruption of the beds at some time after deposition. The principle of cross-cutting relationships states that geologic features, such as dikes and faults, that cut across otherwise continuous rocks formed after the rocks that they cut across. The principle of inclusions states that objects enclosed by rock formed prior to inclusion within the rock.
Answer to Question 2
Answer: Relative ages establish the sequence of a series of events without establishing exactly when each event occurred. To establish relative age, items or events are placed in order of what happened first, what happened next, and what happened last. Absolute ages indicate exactly when an event took place. An absolute age is a specific age in years, or a statement that an event happened a particular number of years in the past.
Motion of the barycenter of the Solar System relative to the Sun
Major Events in the History of Psychology (5 of 6)
Night Attack on the Sanjo Palace (detail), from the Scrolls of Events of the Heiji Period.
Coral bleaching events are becoming more common
Electrical Events
The major events in meiosis in an animal cell with metaphase