Trilobites were rapidly evolving and widespread marine organisms that spanned a number of geologic time periods. Certain types of trilobites only appeared in specific segments of geologic time; therefore, when one of these trilobites is found, you can be certain that the rock layer it is found in is of a certain geologic age.
<span>He alleged that the US State Department had been infiltrated by communists as had Hollywood and other American institutions. This created a paranoic attitude that America was being systematically brought down from within by communists who were trying to take over the world. Consequently many American politicians argued for a stronger line to be taken on communism.</span>
One circumstances that prevented England from expanding its territories quickly as other European nations was that they were basically located in an Island.
