<span>Steno’s final principle is the “principle of lateral continuity,” which says that sediment layers spread out until they reach an obstacle that keeps them from spreading further, the way soup spreads out in a bowl until it reaches the sides of the dish. “Wherever bared edges of strata are seen,” he wrote, “either a continuation of that same strata must be looked for or another solid substance must be found that kept the material of the strata from being dispersed.”
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A. Add up individuals who came into the area because of reproduction or immigration
