Numerous specimens of minerals brought by Lieutenant Graham and Dr. Somerville from the Upper Mississippi and the Illinois rivers and others from that region, now in the possession of Dr. L. C. Beck, of St. Louis, have a peculiar resemblance to similar minerals met with in the Ozark mountains, south of the Missouri. From these resemblances, and the corroborating testimony of all the accounts we have received concerning that country, rich in mines, which lies along the eastern side of the Upper Mississippi, we have been induced to believe that a continuation of the Ozark mountains, or at least, of a region similar in Mineralogical features, extends from the confluence of the Missouri, northward to the sources of the Wisconsan, and the Ontonagon river of Lake Superior, north of the Missouri, the country is very little elevated; but aside from this it appears to possess all the peculiar features of the region we have been considering. The sandstones, the limestones, and other rocks, have a striking resemblance. Both regions abound in the ores of lead, and both afford copper.[89] We are aware that the great irregularity in the direction of the ridges accessory to this range, and of the dip and inclination of the older secondary rocks belonging to it, may be considered objections to our idea of the connection and continuity of the different parts and the general direction of the group. But we are by no means anxious to maintain the position we have assumed. Our examinations have been limited, and we shall rejoice in any opportunity of correcting our errors, and enlarging our acquaintance with this interesting range of country. {313} We subjoin in a note some account of a few of the most interesting minerals hitherto observed in connection with the rocks of this district.[90] _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.