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of the Mesozoic was tropical in Utah, at least, till the beginning of 
in all directions, which must have made the climate very humid 
still and precluded the existence of arid vegetation. Eastern Utah 
of fresh water. But during most of the Tertiary, at least near the 
sea level, the climate still was tropical throughout our region. 
However, in the latter portion of the age, we have unmistakable 
evidence of a temperate climate, though warmer than that of to- 
around the borders of the lakes, as is proved by their fossil re- 
mains in the clay beds, and.even some of the willows and cotton- 
