The River St. Clair is a broad and noble stream, and impressed us as justifying the highest encomiums bestowed on it by Charlevoix, La Hontan, and other early French travellers. We ascended it thirty miles, which brought us to Fort Gratiot, at the foot of the rapid which marks the outlet of Lake Huron. In this distance, we passed, at separate places, nine vessels at anchor, being detained by head winds, and encountered several Chippewa and Ottowa canoes, each of which were generally occupied by a single family, with their females, blankets, guns, fishing apparatus, and dogs. They evinced the most friendly disposition. In landing at Oak Point,[13] I observed a green snake (coluber æstivus) in the act of swallowing a frog, which he had succeeded in taking down, except the extremity of its hind legs. A blow was sufficient to relieve the frog, which still had sufficient animation to hop towards the river. The snake I made to pay the forfeit of his life. [13] Now the site of Algonac. At Fort Gratiot, we were received by Major Cummins, U. S. A., who occupied the post with sixty men. The expedition was received with a salute, which is due to the Governor of a Territory. Two soldiers who were sickly, were here returned, and five able-bodied men received to supply their places, thus increasing the aggregate of the party to forty persons.[14] [14] To cover any arrangements of this kind, general orders had been issued by Gen. Macomb, to the commandants of the western posts. The banks of the River St. Clair are wholly alluvial or diluvial. There is not a particle of rock in place. One idea presses itself prominently to notice, in reflecting on the formation of the country. It is the vast quantum of clay, mixed drift, and boulders, which have evidently been propelled, by ancient forces, down these straits, and afterwards arranged themselves according to affinities, or gravitation. At the precipitous banks between the inlet of Black River and Fort Gratiot, this action has been so clearly within the erratic block period of De la Buck, that it has imbedded prostrate forest-trees, and even freshwater shells, beneath the heavy stratum of sand, resting immediately upon the fundamental clay beds, upon which the city of Detroit, and indeed the alluvions of the entire straits rest.[15] We again encountered at this place, blocks of the primitive or crystalline boulders, which were first seen at Grosse Point. There are some traces of iron sand along the shore of this river, the only mineral body, indeed, which has thus rewarded my examinations. [15] In the artesian borings for water, undertaken by Mr. Lucius Lyon, at Detroit, in 1833, these clay beds were found to be one hundred and fifteen feet deep.--Vide _Historical and Scientific Sketches of Michigan_, p. 177.