THE PHYSICAL FEATURES and the climate of Oklahoma permit a
great diversity of agricultural interests and products. The wide
range in elevation, increasing from the southeast to the north-
west, and the mean annual temperature, which is much higher
in the southeast than in the northwest, make possible the pro-
duction of widely different crops. The rainfall, which de-
creases to a marked degree from east to west, affects agricultural
production, as does the wide variation of soils.

The physiographic regions are usually divided by sharp
boundaries, though they sometimes shade easily from one to
another. Generally the state is divided into mountainous or
hilly areas--the Ozark Mountains in the northeastern part of
the state; the Ouachita, or Kiamichi, Mountains in the south-
eastern; the Arbuckle Mountains in the south-central; and the
Wichita Mountains in the southwestern portion. The plains
or valley regions are separated into seven divisions--the Red
River area south of the Arbuckle and Kiamichi mountains; the
Lower Arkansas Valley between the Ozark and Kiamichi moun-
tains; the Sandstone Hills, which lie west of the lower Arkansas
Valley; the Prairie Plains, which lie west of the Ozark Moun-
tains; the Redbeds Plains, which comprise a wide strip extend-
ing north and south through the central part of the state; the
Gypsum Hills west of the Redbeds Plains; and the High Plains
in the northwestern part of the state. These various regions,
together with other factors, make the state an area of diversified
interests with respect to crops and pasturage.

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