Transactions of the Wisconsin Academy of Sciences, Arts and Letters
volume V (1877-1881)
Swezey, G. D.
On some points in the geology of the region about Beloit, pp. 194-204 ff. PDF (2.6 MB)
Geology of the Rejion about Beloit. in the region as well as at Janesville. Above these are eighteen feet of Lower Blue limestone with two layers of a few inches each in thickness, one highly crystalline, the other very fossilifer- ous, easily recognizable in the three quarries which include this horizon. The Upper Buff limestone has been divided by Prof. Chamberlin into five subdivisions, known by us at Beloit as the Carpenter, Lower Fucoidal, Pseudo-birdseye, Upper Fucoidal and Cherty beds respectively; the lower and upper of these are still further divisible, as shown on the chart, and their divisions recog- nizable throughout the region and questionably as far away as Janesville. The Upper Blue limestone which completes the Trenton section is estimated at twenty feet in thickness, although as we shall see, this cannot be certainly determined. Beginning with Scott's quarry, we have the transitional layers or nearly all of them, and just below, separated by a few feet unexposed, the characteristic St. Peters sandstone; in the Second railroad quarry, a mile and a quarter to the south, we have a por- tion of these lavers exposed, and above them the entire thickness of Lower Buff and Lower Blue, and, in the broken and nearly in- accessible upper layers. probably the lower part of the Upper Buff layers; in two other quirries less than a mile from this, we find the same horizon, including the crystalline and fossiliferous layers before mentioned. In a ravine below Carpenter's quarry also, the Lower Blue layers are exposed. Carpenter's quarry forms the next step in the ladder, and here the exact matching becomes difficult owing to the broken and weathered condition of the top of the second quarry, and so we are obliged to call in the aid of the large quarry west of Janesville, which includes both of these horizons. There is in the very bottom of Carpenter's quarry a well marked shaly seam ; a similar seam is found near the top of the second quarry, eighteen feet above the junction of lower buff and lower blue. At Janesville a seam is found seventeen feet above this junction, and at about this horizon the shaly fossilifer- ous Lower Blue layers pass by insensible gradations into the com- pact, unfossiliferous Carpenter beds. The fact that nearly all the subdivisions are a little thicker at Beloit than at Janesville, makes the difference of a foot in the height of this seam above the june- 197
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