How big are the crystals in quickly cooled volcanic glass?

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

What type of coastline is commonly found along the western side of the america’s

Which of the following is an example of an outdated theory based on the consensus of the scientific community ? a. big bangb. geocentric solar systemc. heliocentric theoryd. plate tectonics answer : geocentric solar system