Maria goes for a hike inside a cave. What types of rocks will she most likely see? A)extrusive igneous
B)metamorphic
C)chemical sedimentary
D)clastic sedimentary

Geologists know that potassium-40 decays to argon-40, with a half-life of 1.3 billion years. if an analysis of a feldspar crystal in a sample of granite shows that 75 percent of the potassium-40 atoms have decayed to form argon-40, what is the age of the granite

These factors threaten north americas ecosystems

Read the article titled "castro resigns." why did the us impose trade sanctions against cuba in 1962?