CAEBOOTFEBOUS SYSTEM. 197 



named place. Near LeGrand, in the eastern part of 

 Marshall county, and only a few miles west of Indiantown, 

 No. 3, of the preceding section is well exposed, showing a 

 thickness of about forty feet from the level of the Iowa river. 

 Nos. 1 and 2 do not appear there, having passed beneath its 

 surface by a westerly dip, aided by the slope of the stream. 

 The exposure here is composed almost entirely of light brown 

 or buff-colored limestone, more or less magnesian; and in 

 some of the more calcareous layers a slight tendency to oolitic 

 structure is seen. Some of the layers are cherty, but a large 

 part of it is quite free from silicious matter. 



The stone is largely quarried for various purposes, and the 

 finer layers, which frequently have a beautiful veining of per- 

 oxyd of iron, are wrought into various ornamental and 

 useful objects, and it is known in the market as "Iowa 

 marble." This stone is further described upon another page, 

 and an analysis of it is given in Prof. Emery's report. 



Several other exposures of the Kinderhook beds are known 

 in Tama and Marshall counties, but those here mentioned are 

 the principal ones. 



Going northward, into Hardin county, we find the rocks of 

 this epoch somewhat changed in iithological characters, 

 particularly at Iowa Falls. At this place, a slight anti- 

 clinal axis, having a northward and southward direction, has 

 brought up these beds, and they have all been cut through by 

 the Iowa river, so that they are well exposed in its banks. 

 They are here composed of two distinct divisions, each about 

 fifty feet in thickness. The lowest is composed of somewhat 

 regularly bedded, tolerably pure limestone, but with little, if 

 any, tendency to oolitic structure, although it is probably the 

 equivalent of the oolitic bed at Indiantown and Burlington. 

 It is soon lost to view by dipping both east war dly and west- 

 wardly from the falls, and receives the upper division upon 

 it. This is a rough, and in most places in this vicinity, a 

 fragmentary and worthless magnesian limestone with occa- 

 sional sandy layers. 



In both of these divisions, fossils of all kinds are rare but 



