Question

When reading a geologic map, rock units are labeled with letter codes. The first upper-case letter indicates _______, while the following lower case letters represent ____.

Answer 1

Answer:

geologic unit

When reading a geologic map, rock units are labeled with letter codes. The first upper-case letter indicates age of the geologic unit, while the following lower case letters represent geologic unit's name or the type of rock of which it is comprised.

Explanation:

Geologist have divided the history of the earth into 4 main periods of time; the Eons, the Eras the Periods and the Epoch. On a geological map, an initial capital letter is usually followed by one or more lower case letters while the lower case letters indicate either the name of the unit, if it has one, or the type of rock, if the unit has no name.