One of the great problems of geology is the explanation of the differences between the climate of the present and that of the past. Today there are great contrasts from zone to zone and from season to season. During much of the past there was relative uniformity from latitude to latitude and from summer to winter. Doubtless many factors helped bring about this change. One factor that appears not to have been discussed, however, is increased salinity of the ocean. There is a general agreement among geologists that the ocean has become increasingly saline throughout the ages. Indeed, calculations of the rate of accumulation of salt have been a favorite method of arriving at estimates of the age of the ocean and hence of the earliest marine sediments. So far as known, however, no geologist or climatologist has discussed the probable climatic effects of increased salinity. Yet it seems . . .