Nature is constantly changing and Beaver Ponds Park is no exception. The ponds here were originally created by the beavers who dammed portions of Beaver Brook until it overflowed. Much of the original vegetation died and was succeeded by aquatic specialists. If the ponds are left undisturbed, they may gradually fill up with sediment and plant decay which will cause the ponds to become marshy over the course of several decades or centuries. Currently, the two ponds on either side of Fournier Street, look very different because they are in different stages of succession.