The Baraboo iron-bearing district of Wisconsin Volume 13

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1904 Excerpt: ...slate Iron ore (mainly) Gray slate i Record furnished by W. 6. La Rue. 0 to 350 350 to 439 439 to 600 600 to... CHAPTER V. THE PALEOZOIC SEDIMENTARY ROCKS. The Paleozoic formations, which throughout the district and elsewhere in Wisconsin and adjoining states lie in approximately horizontal position, consist from the base upward of the following formations: the Potsdam sandstone, the Lower Magnesian limestone, the St. Peter sandstone, the Trenton and the Galena limestone, and probably the Cincinnati shale. The Potsdam sandstone formation occurs on the lower flanks of the quartzite ranges and in the valley bottom, while at higher elevations occur the succeeding formations. The Lower Magnesian limestone formation in this district is mainly conglomerate and sandstone, and in this respect differs from the usual character of the rocks comprising this formation outside the district. Unconformity of Paleozoic and Pre-Cambrian. The general relations of the Paleozoic formations to the Pre-Cambrian formations are shown in the generalized cross section (Pl. XIV). The unconformable relations of the pre-Cambrian rocks to the Paleozoic have already been referred to. The pre-Cambrian formations were elevated and folded into massive mountain ranges and subsequently greatly eroded, long before the hori zontal beds of the Paleozoic were deposited upon them. The unconformity between the Potsdam sandstone and the pre-Cambrian crystallines probably marks one of the greatest gaps, if not the greatest, in the geological column. CROSS SECTION NORTH AND SOUTH ACROSS THE BARABOO DISTRICT TO GIBRALTAR BLUFF. The section is drawn to illustrate the general relations of the pre-Cambrian formations to the Paleozoic formations, and also the height to which the quaruite ranges extend above...