TRENTON LIMESTONE. 301 



tunity for studying its character and fauna, which is very similar to that already given. 

 The uppermost layers of the Trenton, and its junction with the Galena limestone above, 

 may be seen satisfactorily in the N. E. % f Sec. 31, and in the S. E. ^ of Sec. 19, 

 town of Union, where a new species of Stictopora. and one of Trematopora, Ptilodictya 

 recta, Orthis perveta, O.testudinaria, 0. tricenaria, Lcptwna sericea, and Ceraurus pleu- 

 rexanthenius indicate the character of a fauna very abundant in individuals, though not 

 especially so in species. At the lower quarry belonging to Mr. Krump near Ft. Atkin- 

 son, the upper portion of this formation is again shown, though the layers are some- 

 what lower than the above. About two miles below Jefferson, on the west side of Rock 

 river, a little stream has cut down to dark mottled, fine grained, rather thick beds that 

 are capable of receiving an excellent polish. Their lithological affinities are with the 

 upper half of the formation. 



Near Aztalan are several quarries showing the junction of the Lower Buff layers and 

 those above. The fossils collected were chiefly Buif species. The surface of the rock is 

 beautifully polished and striated by glacial action. 



On the north side of Red Cedar Lake in the town of Oakland, and in the vicinity, on 

 the west, the lower beds are displayed, showing a somewhat less firm rock than usual. 

 The first mentioned locality affords Schizocrinus, Stictopora, Orthis perveta, 0. plica- 

 tella? 0. tricenaria, Streptorhynchus felitextum, Strophomena incrassata? Zygospira 

 modesta? Raphistoma lenticularis, Pleurotomaria, Subulites elongatus and Cyrtolites. 

 To which the others add Buthotrephis succiiJens, Strophomena camerata, Cypricardites 

 rotundatus, Orthocems vertebrale, Onnoceras and Gonioceras anceps. 



The most interesting exposure of the Trenton limestone in the town of Waterloo is 

 at the quarry of Mr. David Crump in section 35. The lower four feet are of thick bedded, 

 very serviceable rock, above which lies one foot of thin shaly stone, succeeded by six feet 

 of somewhat irregular layers of medium thickness, upon which are two feet of even 

 bedded stone overlaid by two and a half of thin, greenish, shaly material. The lower 

 portion is to be regarded as representing the Lower Buff layers, and the upper ones 

 the Lower Blue limestone. The following species were collected in a limited time at 

 this locality: Buthotrephis succulens, Graptolite-like bodies; Chcetetes, Streptelasma 

 corniculum, Orthis tricenaria, Streptorhynchus deflectum, S. planwribonum, Stropho- 

 mena incrassata, a new species of Rhynchonella, Tellinomya ventricosa (young) Cyp- 

 ricardites rotundotus, and a new species, Raphistoma lentieularis, Pleurotomaria sub- 

 con ica, Murchisonia bicincta, M. helictercs, Orthoceras annellum, 0. vertebrale, and frag- 

 ments of Onnoceras and Cyrtoceras. 



The Trenton formation outcrops in the towns of Shields, Portland, Elba, Lowell, Cal- 

 amus, Beaver Dam, Westford, Fox Lake and Trenton, in Dodge county; but the ex- 

 posures in all cases are slight, and for the most part belong to the base of the formation. 

 While they subserve a very useful purpose in supplying their respective regions with 

 building material, they add little to our knowledge of the formation, and possess but 

 small interest to the geologist or general reader. 



In the townships of Mackford and Green Lake, in the county of Green Lake, more 

 frequent and extensive exposures, both natural and artificial, occur, particularly in the 

 vicinity of the lakes that beautify those towns. According to the general rule already 

 observed, they are chiefly the lower beds, and are caused to stand forth by the easy 

 degradation of the sandstone below. 



In the vicinity of Ripon the Lower Buff limestone is well displayed. One of the 

 noticeable peculiarities in this neighborhood is the unequal elevation of the base of the 

 formation. While resting, so far as observed, conformably upon the St. Peters sand- 

 stone, the junction is found at varying altitudes. One of the lowest points is at " The 

 Falls," within the city. These falls are caused by the waters of Silver creek pouring 

 over the lower ledges of the Trenton limestone and excavating the softer sandstone be- 



