TRENTON LIMESTONE. SOI 



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 Hmestone above, 

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

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

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

 rexanthemus 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 Jefiferson, on the west side of Rock 

 river, a Httle stream has cut down to dnrk mottled, fine grained, rather thick beds that 

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

 upper half of the formation. 



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

 those above. The fossils collected were cliiefly Buff species. The surface of the rook 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 aftbrds Schizocrinus, Stictopora, Orthis perveta, 0. plica- 

 tella? 0. tricenaria, Streptorhynchus feliteoctum, Strophomena incrassata? Zt/gospifa 

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

 To which the others add Biithotrephis succuJens, Strophomena camerata, Cypricardites 

 rotundatus, Orthoceras vertebrale, Ormoceras 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 85. The lower four feet are of thick bedded, 

 very serviceable rock, above which Kes 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 Hmited time at 

 tliis locality: Buthotrephis succuUns, G-raptohte-Ulte bodies; Chcetetes, Streptelasma 

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

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

 ricardites rotundatus, and a new species, Raphistoma lenticularis, Pleurotomaria sub- 

 conica, Murchisonia bicincta, M. helicteres, Orthoceras annellum, 0. vertebrale, and frag- 

 ments of Ormoceras 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 t« the base of the formation. 

 While they subserve a very useful purpose m supplying their respective regions witli 

 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 aiready 

 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 

 Ealls," 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- 



