"The rock containing these interesting impressions is a compact limestone of a grayish-blue colour. It was originally quarried on the left bank of the Mississippi at St. Louis, and is a part of the extensive range of calcareous rocks upon which that town is built. It contains very perfect remains of the encrinite, echinite, and some other fossil species. The rock is firm and well consolidated, as much so as any part of the stratum. A specimen of this rock, now before us, has a decidedly sparry texture, and embraces a mass of black blende. This rock is extensively used as a building material at St. Louis. On parting with its carbonic acid and water, it becomes beautifully white, yielding an excellent quick-lime. Foundations of private dwellings at St. Louis, and the military works erected by the French and Spaniards from this material sixty years ago, are still as solid and unbroken as when first laid. We cite these facts as evincing the compactness and durability of the stone--points which must essentially affect any conclusions, to be drawn from the prints we have mentioned, and upon which, therefore, we are solicitous to express our decided opinion."--FLAGG. [102] For the history of Fort Chartres, see A. Michaux's _Travels_, in our volume iii, p. 71, note 136. For a biographical sketch of St. Ange, see Croghan's _Journals_, in our volume i, p. 138, note 109.--ED. [103] At the close of 1767 Captain Francisco Rios arrived at St. Louis in pursuance of an order of D'Ulloa, governor of Louisiana. The following year he built Fort Prince Charles, and although at first coldly received, won the respect of the inhabitants by his tact and good judgment. After the expulsion of D'Ulloa in the revolution of 1768, Rios returned with his soldiers to New Orleans.--ED. [104] Spain retroceded Louisiana to France by the treaty of San Ildefonso (October 1, 1800). The latter transferred the territory to the United States by the treaty signed at Paris, April 30, 1803. The attack on St. Louis mentioned by Flagg, occurred May 26, 1780. The expedition, composed of Chippewa, Winnebago, Sioux, and other Indian tribes, with a Canadian contingent numbering about seven hundred and fifty, started from Mackinac. See R. G. Thwaites, _France in America_ (New York and London, 1905), p. 290; and "Papers from Canadian Archives," _Wisconsin Historical Collections_, xi, pp. 152-157.--ED.