214 Reviews and Notices of Books* 



The greater part of tlie State rests on the palaeozoic formations, 

 the wliole of which from the Permian to the Lower Silurian in- 

 clusive are represented. The points of difference between these 

 formations in Iowa and in the Eastern States and British 

 America are such as the following. The Permian system, wanting 

 in the East, makes its appearance in Iowa and the neighbouring 

 region of Kansas where it was first recognised. The coal meas- 

 ures thin out, while the carboniferous limestone, largely developed 

 in Nova Scotia, but nearly absent in the region of the Appalachians? 

 re-appears in great force in the west, and with very remarkable 

 differences in its fauna. The various members of the Devonian 

 and Silurian systems are represented, but with the exception of 

 the Niagara limestone and Potsdam sandstone, with diminished 

 thickness. The only formation newer than the Permian as yet 

 recognized in Iowa, is the Cretaceous which has not as yet been 

 fully examined. 



All there formations are spread out in an undisturbed and 

 slighly inclined position, and their principal useful minerals are 

 coal, galena, and gypsum. The coal measures have an aggregate 

 thickness of only about 100 feet, and appear to include only two 

 beds of coal, the most important of which sometimes attains a 

 thickness of four feet. The coal seams are by no means regular, 

 but have probably been affected in their original deposition by 

 many local disturbances ; a remark which applies to these old fossi- 

 lized bogs much more generally than persons who have not studied 

 the coal measures in detail are aware of. The coal of Iowa is 

 bituminous, and of various qualities in reference to the quantity of 

 earthy matter contained in it. 



The lead region of Iowa is a continuation of that of Upper 

 Missouri. The mineral occurs in vertical fissures widening into 

 large cavities or caverns, filled with clay and ore, or with compact 

 ore, and sometimes communicating with flat tabular expansions 

 or beds. These deposits occur principally in the " Galena Lime- 

 stone," but are also found in diminished extent in the Trenton 

 limestone which immediately underlies it. They appear to be quite 

 wanting in the overlying formations. 



The Gypsum occurs in rocks probably of Permian age, but their 

 detailed examination is not included in this portion of the report. 



The second part is devoted entirely to the fossil remains of the 



