Used today by much of the world, the Gregorian calendar is based on A. the ancient Hebrew calendar.
B. the Islamic calendar.
C. the cycles of the moon.
D. the movement of Earth around the sun.

Gemstones are commonly found in pegmatites, which are igneous rocks that are a. exceptionally mafic b. exceptionally coarse grained c. exceptionally fine grained d. extrusive, forming from lava

What kind of fault is the san andreas fault

What's a recharge area? a. the part of an aquifer where groundwater meets a lake or stream b. the part of an aquifer where surface water reaches the water table c. the part of an aquifer that's located between two aquicludes d. the part of an aquifer that's located at a lower elevation