SEDIMENTARY ROCKS OF EASTERN WISCONSIN. 



453 



dred and fifty feet above the streams, we discovered no land apparently higher. 

 The red clay, as I have before stated, covers the rocks ; and this, with the universal 

 drift, effectually conceals them from view in the lower portion of the country. 



The limestones, when visible, show but indistinct lines of stratification, and there- 

 fore their dip and thickness could not be measured, or even well estimated. Their 

 fossils are not abundant or perfect ; wherefore little can be done at present towards 

 classifying them in detail. At only three points did we perceive the junction of 

 the quartzose sandstone with the calcareous sand-rock that rests upon it. The 

 sand-rock was nowhere seen in contact with the igneous rocks of the interior, but 

 the outline or boundary of those rocks is very manifest in giving a peculiar contour 

 to the overlying drift. 



On the map, I have shown by deeper colours the places where the rocks are 

 visible, and in fainter dashes of the same colours, given my conjecture of the limits 

 of the formations between the points where they are seen. 



An important object in the examination of the granites, syenites, and metamor- 

 phic rocks of the interior, was a hope that they might here, as in the Dead River of 

 Michigan and on the Bad River of Wisconsin, contain important beds of iron ore. 

 Although, as far as we went, the formations closely resembled the Dead and Bad River 

 regions, we saw no beds or veins of ore ; but from the extent of resemblance, should 

 anticipate the presence of iron further towards the interior, than our route. A por- 

 tion of this region has been surveyed into townships by Mr. Ellis, of Green Bay, and 

 Mr. Conkey, of Grand Chute, and some of it subdivided into sections. Mr. Ellis closely 

 observed the rocks over which he passed, took specimens, and made memoranda ; 

 and these, for Ranges 20 and 21, Townships 34 to 48, on the Menomonie River, are 

 valuable contributions in disclosing the geology of the country. He found here granite, 

 S} 7 enite, and hornblende rocks. These gentlemen, in their surveys, report no beds of 

 iron ; and their returns of the variation of the needle (a sure index of the presence of 

 the magnetic oxides), as given me by the Surveyor-General, show but two or three 

 cases of irregularities ; and these may be charged to trappose rocks, into which iron 

 enters as a constituent. On the low grounds about Green Bay, and on other low 

 lands, and about springs, near the rivers that flow into the Bay from the west, are 

 patches of bog ore ; but these alluvial deposits are so irregular in extent, depth, 

 quality, and richness, that they are an uncertain reliance, and to be confided in 

 only after a faithful examination, by means of pits sunk in various parts of each 

 bed. The metal produced from such ores is easily wrought, and of a good quality. 



Sedimentary Rocks in the Eastern Part of Wisconsin. — The only formation east of 

 the Wisconsin and Rock Rivers, that can be regarded as fixed beyond doubt in 

 geological position, is a limestone, the equivalent of the " Trenton" of New York, 

 and the Blue Limestone of Cincinnati. Neither the rocks above or below the Blue 

 Limestone have been studied sufficiently to subdivide them into formations ; nor 

 has the extent of country occupied by each on the waters of Green Bay and Lake 

 Michigan, been exactly determined. The difficulty of getting a sight of the rocks, 

 owing to the accumulation of drift, and the scarcity of fossils, where they are visi- 

 ble, sufficiently explains why a classification cannot as yet be made. 



