Recapitulation
The Ozark mountains extend from the sources of the Rio Colorado of Texas on the south-west, to the confluence of the Mississippi and Missouri on the north-east, and are continued in a low range from this point towards Lake Superior. They are widest in the south-west, and in that quarter they mingle with some low tracts of secondary sandstone, extending from near the Gulf of Mexico to the base of the easternmost ridge of the Rocky Mountains. Whether there is any similar expansion at the northern extremity, or whether this range is connected as a spur to the great primitive chain supposed to exist north of the great lakes, and is separated by a wide secondary and alluvial valley from the Rocky Mountains, is yet to be determined. This range consists of low ridges, irregular in direction, rarely rising to an elevation of more than 1500 or 2000 feet, and consisting principally of secondary rocks.
The strata are—
1st. Granite—at the cove of the Washita.
2d. Argillite—ranging north-east and south-west from Little Rock on the Arkansa to the hot springs, and thence to the sources of the Kiamesha.
3d. Transition Sandstone—a narrow margin, following nearly the same direction on the north-west side of the argillite, and usually inclining like it to the south or south-east.
4th. Flint (petrosilex)—From the hot springs north-east to the Mississippi, and usually forming the basis of the pine-lands.
5th. Limestone—Compact and sparry; distributed {314} in the same direction as the last, but more extensive.
6th. Argillaceous Sandstone—with extensive beds of coal, and abounding in mines of lead.
7th. Alluvial—There are many extensive tracts of deep argillaceous or calcareous loam; in other instances, a more meagre soil has resulted from the disintegration of the sand-rock.