crater – n. a large hole in the ground

geologist – n. a scientist who has studied rocks and soil in order to learn about the history of planets

cliff – n. an area of high, steep rocks

sediment – n. a solid substance that forms a layer at the bottom of a liquid

resolution – n. a measure of sharpness for an image

three-dimensional – adj. appearing to have length, depth and width

terrestrial – adj. relating to the Earth, not space

host – v. to serve as a host for something

puzzle – n. a game or activity in which you have to put pieces together or answer questions using skill

crucial – n. extremely important or necessary