Description/List Cause/Effect Sequence Problem/Solution Compare/Contrast Text Structure Text *The earth's crust is made up mostly of hard, rocky substances, though some of these substances have crumbled into dirt from years of exposure to wind and rain and roots of plants. That crust is many miles thick (though the part under the ocean is thinner than the part on the land). Underneath the crust is a layer called the mantle. The mantle is about 1.800 miles thick. Below the mantle is the earth's core, which is made up of two layers called the inner core and outer core." - Christopher Lampton. Earthquake. 1991​