Which of the following best describes the climates of europe and north america during the 1.8 million years of the quaternary period? a. hot and dry b. cool and rainy periods followed by droughts c. warm and mild d. a series of ice ages followed by periods when the glaciers melted.

organ system-an organ system is a group of organs that work together to perform one or more functions. each does a particular job in the body, and is made up of certain tissues.

answer:

convection currents in the magma drive plate tectonics. heat generated from the radioactive decay of elements deep in the interior of the earth creates magma (molten rock) in the aesthenosphere. the aesthenosphere (70 ~ 250 km) is part of the mantle, the middle sphere of the earth that extends to 2900 km.