gannite

Clark and myself walked to the white earth river which approaches the Missouri very near at this place, being about 4 miles above it's entrance. we found that it contained more water than streams of it's size generally do at this season. the water is much clearer than that of the Missouri. the banks of the river are steep and not more than ten or twelve feet high; the bed seems to be composed of mud altogether. the salts which have been before mentioned as common on the Missouri, appears in great quantities along the banks of this river, which are in many places so thickly covered with it that they appear perfectly white. perhaps it has been from this white appearance of it's banks that the river has derived it's name. this river is said to be navigable nearly to it's source, which is at no great distance from the Saskashawan, and I think from it's size the direction which it seems to take, and the latitude of it's mouth, that there is very good ground to believe that it extends as far North as latitude 50°. this stream passes through an open country generally. the broken hills of the Missouri about this place exhibit large irregular and broken masses of rocks and stones; some of which tho 200 feet above the level of the water seem at some former period to have felt it's influence, fo they appear smoth as if woarn by the agetation of the water. this collection consists of white & grey gannite, a brittle black rock, flint, limestone, freestone, some small specimens of an excellent pebble and occasionally broken stratas of a stone which appears to be petrefyed wood, it is of a black colour, and makes excellent whetstones.

William Clark - The Journals of Lewis and Clark, 1804-1806