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The Maya chronology and traditions indicate that this was probably at the same time when moister conditions apparently prevailed in the subarid or desert portions of the United States and Asia.

But the prairies lie between the more humid forest-covered regions on the east and the less humid or subarid plateaus on the west, 251 and during the summer season droughts and hot, scorching winds are of common occurrence.

Subarid in character, except to the north and at high elevations, the vast mining interests of the region and its treeless surroundings give this forest an economic value out of proportion to the quantities of timber it contains.