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Geology-Limestone District

IV. The next and last Geological District into which this Territory may be naturally divided should be called the Limestone District as it is composed almost exclusively of limestone rock, and extends from Lake Michigan west to the other districts mentioned. This same [extensive] great deposite of calcareous rock extends [a great distance] south into Illinois where it dips under the rocks of the "Coal Formation", and north it continues along the lake shore as far as Mackina. It generally occurs in thin compact layers or strata disposed horizontally, or nearly so, of a light grey color, and affording very pure lime when burned. At other places it is of a dirty yellow color filled with minute pores and easily decomposed, when exposed to the air and weather. It is [but] very sparingly supplied with organic remains or petrifactions, but such as are found indicate this deposite to be the "Carboniferous Limestone" of geologists* which forms the basis on which rests the coal bearing rocks. It appears then from these facts that

*It is probable that this great limestone deposite will be found upon further examination to belong to different formations or eras; all however below, or older than, the coal measures.

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