Volcanic origin of submarine mountains. Dark cross hatched pattern represents coral. Stippled areas around volcanoes represent sediment. Some of these cones may grow to rise above sea level, forming islands like the Hawaiian chain or the Philippine Islands. Coral reefs growing around the subsiding volcano may form an atoll .
Guyots are seamounts with flat tops.
A bathymetric map is made just like a topographic map. Once the contour lines are drawn, a two-dimensional picture of the ocean floor or lake bottom becomes visible. Tape model securely to the bottom of a cardboard box . Tape the lid in place. The grid paper on top of the model does not need to be replaced at the end of each class session.