INTERMEDIATE COUNTRY IN THE DIRECTION TO GREEN BAY.--There is a line which separates, on the north, the granitical and trap region from the metal-bearing limestone, and its supporting sandstone. This formation of the elder series of rocks, having been traced to the south shore of Lake Superior, and having been seen to constitute the supporting bed of the alluviums and diluviums of the Upper Mississippi, above the Peace Rock, it may subserve the purpose of inquiry to trace this line of junction by its probable and observed boundaries. The line may be commenced where it crosses the Mississippi, at the Peace Rock, and extended to the St. Croix, the falls of which are on the trap-rock, to the sources of the Chippewa at Lac du Flambeau, and the Wisconsin near Plover Portage. The source of Fox River runs amid uprising masses of sienite, and this formation appears to pass thence northeasterly, across the Upper Menominee, to the district of the Totosh and Cradle-Top Mountains, west of Chocolate River, on the shores of Lake Superior. I observed the crystalline sandstone and its overlying cliff limestone, along the valley of the Wisconsin, where ancient excavations for lead ore have been made. There is an entire preservation of its characters, and no reason occurs why its mineralogical contents should not prove, in some positions, as valuable as they have been found in Missouri, or in the Dubuque district west of the Mississippi. On reaching the Wisconsin Portage, the limestone is found to have been swept by diluvial action, from its supporting sand rock. Such is its position not far north of the highest of the four lakes, and again at Lake Puckway, in descending the Fox River; consequently, there are no lead discoveries in this region. On coming to the calcareous rock, which is developed along the channel of the river, below Winnebago Lake, it appears rather to belong to the lake system of deposits. Its superior stratum lies in patches, or limited districts, which appear to have been left by drift action. Petrefactions are found in these districts, and the character of the rock is dark, compact, or shelly. The lower series of deposits, such as they appear at the Kakala Rapids, at Washington Harbor, in the entrance to Green Bay, and in the cliffs north of Sturgeon Bay and Portage, are manifestly of the same age and general character as the inferior stratum of Michilimackinac and the Manatouline chain.