GALENA LIMESTONE. 309 



mined species of Streptelconta, a new species of Lingula, Oiihis lynx, tricenaria. a 

 Strop Jiomena, Cypricardites rotundatus, C. subtruncatus, C. ventricosus, Raphistoma len- 

 ticitlaris, Trochonema umbiUcatum, a new species of Murchisonia and Orthoceras junce- 

 i(t. The most southerly exposure of this formation, seen in Walworth county, was near 

 Sharon Mills. Between this point and Whitewater, deep drift conceals it. Near 

 the latter point, several quarries have been opened, from which a supply of building 

 stone and lime are derived. The rock here is of a more decided buff color than is com- 

 mon, and is marked with peculiar concentric wavy lines of a redish hue. It is soft, po- 

 rous, granular, uneven in texture, and much decomposed on the surface, but is more 

 cohesive and enduring than its appearance would indicate. There is evidence of a con- 

 siderable fauna at this point, though the preservation of the fossils is usually poor. 



The following identifications have been made, a portion of them based on specimena 

 from the private collections of Mr. L. C. Wooster: 



Receptaculites globosus, R. Oweni, Astylospongia, casts of the cup of a Zaphrentis, 

 Cornulites-like tubes, Lingula quadrata, a Monomerella, Orthis lynx, 0. perveta, or equi- 

 rahis, Streptorhynchus deltoideum, Strophomena alternate, S. camerata, large form, S. 

 camerata?, small ventricose form, Atrypa bisulcata, Rhtjnchonella capax, Anibonych'm 

 erecta?, A. lamellosa, Cypricardites ventricosus, Raphistoma lenticularis, Trochonema 

 umbilicatum, Pleitrotomaria, resembling P. Occidentalis, Murchisonia bellicincta, or M. 

 major; M. bicincta, and anew species, Holopea paludiniformis, H. near H. obliqua, 

 Fusispira elongat-t, F. ventricosa, and a new species of Ecculiomphalus, Maclurea 

 Bigsbyi?, and two n. sp. Conularia Trentonensis, Orthoceras planoconvexum, and two 

 undetermined species, Cyrtoceras (Oncoceras) plebeium, and two undetermined species. 



Passing by several minor exposures, we find about two miles southeast of Fort 

 Atkinson, quarries situated in the lower portion of this formation, and a little to the 

 north (Sec. 10, S. E. qr., T. 5, R. 14), a quarry in the Upper Blue limestone. The rock 

 from the former furnishes a good lime and an ordinary building stone. On the west 

 side of Rock river, in the towns of Jefferson and Oakland, are several patches of 

 Galena limestone, forming the nucleus of the prominent hills of that region. On the 

 east side of the river, the heavy drift accumulations effectually conceal the formation. 



About two miles north of Watertown, in the S. E. qr. of Sec. 20, town of Emmet, 

 Dodge county, is an extensive quarry displaying this formation, which still maintains 

 the characteristics already described. Cavities in the rock are rather more than usually 

 abundant, and are usually lined with calcite, or more rarely dolomite, and occasionally 

 with zinc blende or galena. Iron pyrites also occur in nodular crystallizations, many 

 of which are desulphurized in whole or in part. 



Chert, as usual, is abundant, more particularly in the upper layers. Fossils are rare. 



An analysis by Mr. Bode of chippings from the several layers representing a thick- 

 ness of fifteen feet, shows the following composition: 



Carbonate of lime 54.051 



Carbonate of magnesia 44. 139 



Silica 1 . 564 



Alumina 0.072 



Oxide of iron . 174 



100.000 



From which it will be seen to be a nearly pure dolomite, aside from the chert, which 

 was excluded from the specimens analyzed. 



As far north as this point, the rock of this formation has maintained a very constant 

 character, and, as remarked before, closely resembles the Galena in its more typical 

 localities. To the north of this point it begins to undergo a change. For twenty-five 



