On the 25th, being the day after my arrival, I met the assembled, Sioux, in council, at the Agency House, the commanding officer being present, and having finished that business, and finding the Sioux wholly unconnected with, and disapproving the proceedings of Blackhawk and his adherents, I embarked early the next morning on my return to Lake Superior. I reached the mouth of the River St. Croix, at three o'clock P. M. on the 26th, and having entered the sylvan sheet of Lake St. Croix, ascended it to within a few miles of its head, and encamped. Lieut. Allen did not reach my camp, but halted for the night some seven or eight miles short.[191] This lake is one of the most beautiful and picturesque sheets of water in the West, being from two to three miles wide, and some four-and-twenty or thirty in length.[192] The next morning I reached the head of the lake after a couple of hours of travel, and, by a diligent and hard day's work, during which we passed between perpendicular walls of sonorous trap-rock, reached and encamped at the falls of St. Croix, at eight o'clock in the evening.[193] We were now about fifty miles from the line of the Mississippi River. For the last few miles, there had been either a very strong current or severe eddies of water, around angular masses of trap-rock; and we were encamped at the precise foot of the falls, where the river, narrowed to some fifty feet, breaks its way through trap-rock, falling some fifty feet in the course of six hundred yards. We had been carried, at a tangent, from the great Mississippi series of the silurian period, beginning at St. Anthony's Falls, to the vitric formations of trap and greenstone of the Lake Superior system, and were now to ascend a valley, in which a heavy diluvial drift and boulder stratum rested on this broken and angular basis.[194] On reaching the summit of the St. Croix, there are found vast plateaux of sand, supporting pine forests; and on descending the Misakoda, or Brulé of Fond du Lac, the sandstone strata of that basin are again encountered. This ascent was rendered arduous, from the low state of the water. I reached Snake River on the 30th, had an interview with the Buffalo chief (Pezhikee) and his subordinates; finding the population 300, with thirty-eight half breeds. The men, while here, cut their feet, treading on the trap-rock debris, in the mouth of the river. The distance thence to Yellow River is about thirty-five miles, which we accomplished on the 31st, by eight o'clock in the morning, having found our greatest obstacle at the Kettle Rapids, which discloses sharp masses of the trap-rock. The river, in this distance, receives on its right, in the ascent, the Aisippi, or Shell River, which originates in a lake of that name, noted for its large unios and anadontas.