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. These are the remarks we have been able, from observation, to make respecting the geology of a part of the United States' territory, west of the Mississippi. Relating to that part of the interior of our country which lies north-west of Lake Superior, and north of the sources of the Missouri, we have little satisfactory information. From the accurate and intelligent Mackenzie,[91] we are however able to collect a few important particulars. This enterprising voyager, it is well known, travelled from Montreal, L. C., in latitude 45° 30´, longitude 74°, in a north-west direction, to the mouth of Mackenzie's river, latitude 69°, longitude 135°; and again, at a later period, leaving his former route at the Lake of the Hills, about midway between Lake Superior and the mouth of Mackenzie's river, he ascended, in a south-west direction, the Unjegah, or River of Peace, to the Rocky Mountains, and crossing them, fell upon the sources of the northern branch of the Columbia, and from thence arrived at the Pacific, at a point a little north of the inlet of Queen Charlotte's sound. From him we learn that the Rocky Mountains continue in an uninterrupted chain, from the sources of the Missouri in the south, to a point beyond the sixty-fifth parallel of north latitude, near the mouth of Mackenzie's river. The River of Peace which he ascended in his journey to the western ocean, has its source in these mountains in about 55° north, nearly opposite to those of the great northern branch of the Columbia. Farther towards the south are the sources of the Saskatchawin, a large river, discharging itself from the {315} north-west into Lake Winnipic. The mountains in this part seem to be less elevated than those more to the south, but in other respects entirely similar. Their northern termination, according to this traveller, is in about north latitude 65°, 130° west longitude. Santa Fé in New Mexico is in latitude 36°, longitude 104° 53´ west.[92] From this it will be perceived, that the general direction of this great mountain range is nearly from north-north-east to south-south-west. We have no evidence to confirm the conjecture, which, nevertheless, is highly probable, that the principal ridges of this range consist through their whole extent of granite or other primitive rocks.