August 18th. In speaking of a country whose geography is so little known as that of the region S. W. of the Arkansa, we feel very sensibly the want of ascertained and fixed points of reference. Were we to designate the locality of a mineral, or any other interesting object, as found twenty or thirty days' journey from the Rocky Mountains, we should do nearly all in our power; yet this sort of information would probably be thought vague and useless. The smaller rivers of this region have as yet received no names from white hunters; if they have names among the Indians, these are unknown to us. There are no mountains, hills, or other remarkable objects to serve as points of departure, nearer than the Rocky Mountains and the Arkansa. The river itself, which we supposed to be the Red river of Natchitoches, is a permanent landmark; but it is a line and not a point; and aids us only in one direction, in our attempts to designate locality. The map accompanying this work was projected in conformity to the results of numerous astronomical observations for latitude and longitude; but many of these observations were made at places which are not, and at present cannot be known by any names we might attempt to fix upon them.[64] More extensive and minute examination than we have been able to bestow might establish something like a sectional division, founded on the distribution of certain remarkable plants. The great cylindric cactus, the ligneous rooted cucumis, the small-leaved elm, might be used in such an attempt; but it is easy to see that the advantages resulting from it, would be for the most part imaginary.
Discussions of this sort have been much insisted on of late, and may be important as aiding in the geography of climates and soils, but can afford little assistance to topography.
{ 319} The geognostic features of the region under consideration, afford some foundation for a natural division, but this division must be so extremely general as to afford little satisfaction. We could only distinguish the red sandstone, the argillaceous sandstone, and the trap districts, and though each of these have distinctive characters not easy to be mistaken, they are so irregular in form and position, as to be in no degree adapted to aid in the description and identifying of particular places. On the contrary, it is to be regretted there are no established points to which we might refer, in communicating what we have observed of the position of these formations, and indicating the particular localities of some of the valuable minerals they contain.