300 GEOLOGY OF EASTERN WISCONSIN. 



Orthoceras junceum. Worm borings. 



Orthoceras planoconvexum. Illtenus ovatus. 



Orthoceras Beloitense. Asaphus Barrandi. 



Orthoceras 2 sp. undes. Asaphus lowensis. 



Orthoceras vertebrale. Ceraurus pleurexanthemus. 



l/13ndoceras annulatum. Encrinurus sp. undes. 



Endoceras proteifonue. Leperditia fabulites. 

 Gonioceras anceps. 



In the vicinity of Janesville are a number of extensive quarries and natural expo- 

 sures that display the three lower members of the formation quite extensively. At the 

 quarry, a mile and a half west of the city we find, at the base, heavy buff layers, con- 

 taining but few fossils, and representing the Lower Buff beds. The complete tliickness 

 is not shown. On these repose thinner bedded, eminently fossiliferous, blue and gray 

 beds attended with shaly layers and seams. These are the Lower Blue beds, in thick- 

 ness, 22 feet 9 inches. These support about 13 feet of light buff colored limestone, of 

 uneven structure owing to earthy or soft granular spots and occasional cavities rather 

 irregular fracture, giving an earthy surface with crystalline spangles, and containing 

 but few fossils. Beds one foot or less in thickness. These constitute the lower portion 

 of the Upper Buff beds. The following species were observed at this point, nearly all 

 belonging to the Blue beds: Bttthotrephis, Chcetetes lycoperdon, Cr'moid stems, Stic- 

 topora (two new species), Ptilodictya, Trematopora, Lingula attenuata, Orthis perceta, 

 0. tricenaria. 0. sp. new (like 0. testudinaria), Streptorhynchus deflectum, Strophomena 

 camerata, S. incrassata, Rhynchon-aella, n. sp., Ambonychia lamellosa, Tellinomya n 

 sitta, Cypricardites rotundatus, C. ventricosus, Modiolopsis plana, Helicotomaplanulata, 

 Raphistoma lenticularis, Trochonema umbilicatum, Murchisonia helicteres, M. tricari- 

 nata, Pleurolomaria subconica, Bucania, n. sp., Pterotheca attenuata, Hyolithes Baconi, 

 n. sp,, Orthoceras junceum, 0. vertebrate, 0., n. sp., Endoceras, Proteif or me, Cyrtoceras 

 Pandion? Gomphoceras? Asaphus Barrandi, I llctmus ovatus, Ceraurus pleurexanthe- 

 mus, Leperditia fabulites and Beyrichia. 



At the lower railroad bridge at Janesville, the whole of the Lower Buff limestone is 

 shown resting upon the St. Peters sandstone, and overlaid by about 30 feet of the higher 

 beds, which are here less fossiliferous than usual. A section of this exposure is given in 

 the report of 1862. About two miles above the city, Eock river cuts through the lower 

 part of the formation and into the St. Peters sandstone, and a ravine coming in on the 

 east, through which the road ascends from the river, exposes a large part of the higher 

 strata, so that by combining the sections, nearly the whole of the series may be studied. 

 Fossils are abundant in the usual layers. 



Farther up the river, above Fulton Center, the lower strata crown the bluffs with 

 weather-worn outliers, while nearer the water's edge the St. Peters sandstone discovers 

 itself. They become somewhat cavernous at one point, a rare feature in this region. 

 The following fossils were collected along the ledges on the west side of the river: 

 Ch(etetes, Streptelasma corniculum, Stictopora, n. sp., Orthis pen-eta, 0. tricenaria, 

 Streptorhynchus deflectum, Strophomena camerata ? S. incrassata, Rhynchonella, Telli- 

 nomya nasuta, Cypricardites Canadensis, C. rectirostris, C. rotundatus, C. ventricosus, 

 Modiolopsis superba, Raphistoma lenticularis, Trochonema ambiguum, Pleurotomaria 

 subconica, Murchisonia tricarinata, Bucania tidorsata, Pterotheca attenuata, Orthoceras 

 junceum, 0. vertebrale, Ormoceras, Illcenus taurus, Leperditia fabulites. 



The lower beds are also exposed at the outlet of Lake Koshkonong. In the west- 

 ern part of Rock county there are numerous outcroppings of this formation, most fre- 

 quently of the lower beds; but occasionally also of the higher ones. The-railway cut 

 near Magnolia station exposes the Lower Buff beds, and furnishes an excellent oppor- 



