Rocks
used for chalkboards
slate
used to write on chalkboards
chalk
using natural resources wisely
conservation
floats
pumice
shiny black rock used for arrowheads
obsidian
rivers of ice that move very slowly
glaciers
used to make the Washington Monument
marble
made from layers of sand
sandstone
the wearing away of the earth's topsoil
erosion
made from seashells
limestone
made from mud or clay
shale
a deposit of sand and soil at the mouth of some rivers
delta
Pebbles or cobbles cemented together
conglomerate
forms most of the earth's crust under the continents
granite
matter that settles to the bottom or sides of a body of water.
sediment