The mixture of gravel, sand, and crushed stone called is an extremely useful construction material.

While most people who lived in ancient egypt and the middle east avoided settling in nearby deserts, those regions protected them from their enemies. why do you think this was true?

How do oceanographers measure the salinity of ocean water?

If we represent the solar system on a scale that allows us to walk from the sun to pluto in a few minutes, then a) the planets are microscopic and the stars are millions of miles away. b) the planets are the size of basketballs and the nearest stars are a few miles away. c) the planets are marble size or smaller and the nearest stars are thousands of miles away.