Fauna of the Niagara and XJ^jper Silurian Rocks. 123 



If we examine the lowest depths of the sole of Schoonmaker's 

 quarry, we find the same characteristic rock, containing the Tere- 

 hratulous fossil, Gypidean occidenialis, belonging to the Byron 

 division of the Mayville bed. This formation was quarried to 

 some extent, and formed dressed stones, for bases to grave -stones, 

 and window caps and sills. 



This stratum terminated abruptly in an ancient river bed,'the bot- 

 tom of which is smooth and polished, grooved and scratched by 

 the drift of the glacial action or era, for huge granite boulders were 

 excavated during the process of quarrying. 



Above this stratum, are regular even layers of a glazed, compact, 

 metalic ringing, cherty limestone, of several inches in thickness, 

 which is quarried in regular rectangular forms, and is utilized as a 

 durable pavement on the side walks, or macadamized streets of 

 Milwaukee and Waukesha. This formation was covered with ani- 

 mal life, similar to that, so extensively intermixed in the strata or ■ 

 groups overlying it, and is well exhibited at every exposure of 

 this rock, in all the quarries in Milwaukee, Eacine and Wauke- 

 sha counties. But the fauna which covered the surface of the 

 Waukesha limestone, at Cook's, Hadfield's and Pelton's, in Wau- 

 kesha county, or Trimbone's, Swan's, Busack's, Schwackhart's 

 and Story's in Milwaukee county ; or Ives', Horlick's and others, 

 in Racine county ; or Cook and Mc'Henry counties in Illinois, 

 are in an exceedingly compressed stratum, and in many instances 

 the fossils are in such a state as to be but little better defined, than 

 well marked outlines of the original plant or invertebrate animal. 

 In several of the quarries, as Story's, Schewickhart's, Busack's 

 and Cook's, the Bryozoa, Cephalopoda, Casteropoda, Brachiopoda 

 and Crustacea, are so intensely compressed and distorted and glaz- 

 ened as often to give the appearance of different genera or species. 



In seeking an elucidation of the age and character of the dolo- 

 mitic formations in eastern Wisconsin, and in taking into consid- 

 eration the totality of their surroundings, a plausible, perhaps a 

 correct theory is established from these facts. Adopting the axi- 

 oms, that the predominating fossil contents of rocks determine 

 their age and character, we find lying above the regular strati- 

 fied rocks of the Niagara period, and termed the Waukesha lime- 



