Smaller rivers or streams that flow into the larger river.

Scientist who study the origin, history, and composition of Earth’s

            crust.

A low grade of coal.

The distance east or west of the prime meridian.

Refers to the natural vegetation of a region

The distance north or south of the equator.

Windblown dust that accumulates and forms a ridge of bluffs as it

            approaches higher elevations.

The area of land that drains into the tributaries and eventually into

            the larger rivers.

The imaginary line that runs from North Pole to South Pole 

                   through Greenwich, England.

Refers to the animal life of a particular area.

The number of days between the killing frost in the spring to the

              first killing frost in the fall.

Soil that is deposited by running water.

Referred to “water farming”, commercial production of freshwater

              animals.

The imaginary line that goes around the globe halfway between

              the North and South Poles.