In the Middle Ages, most scientists believed that the world was made from four simple elements
and that almost everything was a mixture.
Which type of pure substance had they not
yet discovered?

Astream of surface water reaches a porous portion of sediment and seeps into the ground. this water eventually joins a large reservoir of water located beneath the earth's surface. the example above describes the interacting with the a. cryosphere; biosphere b. hydrosphere; biosphere c. hydrosphere; geosphere d. cryosphere; geosphere