The term “delta area” refers to a region roughly 40 miles long and 15 miles wide situated 65 miles east of San Francisco Bay where the San Joaquin and Sacramento Rivers join and enter Suisun Bay. The waterways in this area are fresh water from these rivers, but they are affected by the ocean tides and to some extent by the salinity of the ocean water. The rgeion ecompasses about 507,000 acres, most of which has been reclaimed for agricultural purposes by the construction of levees to contain the tides and high waters. The word “islands” is used locally to designate this area. The part played by beavers in the exploration and colonization of this nation was a very important one. The fur trappers in their quest for new areas in which to trap, vigorously explored unknown regions. Knowledge concerning the geography of the new land was passed on the colonists who were eagerly seeking new and suitable sites for home and farms. Thus did the beaver and other fur-bearing animals indirectly speed the development of the nation.