**Sea Floor Spreading Model **

a) Graph the age of the sea floor on the Y-axis against the distance from the ridge (on the X-axis). From this graph determine the spreading rate for each geologic interval represented, averaging the two values determined for eastward and westward spreading. Graph these spreading rates (Y-axis) as a function of time (in millions of years, on the X-axis).

b) How has the Atlantic spreading rate varied over the last 200 million years?

(from "The Earth System by, Kump, Kasting, and Crane , Prentice Hall, 1999)