342 A. W. GRABAU — PALEOZOIC CORAL KEEPS 



observed were 28 degrees, decreasing rapidl}^ to 18 degrees; but Cham- 

 berlin mentions a dip of 54 degrees close to the reef, observed while the 

 face was well exposed in quarrying. Other dij)s mentioned b}' Cham- 

 berlin are 30, 31, and 34 degrees, beside those of lower angle. Cham- 

 berlin also mentions the increase in thickness of the sedimentary layers 

 toward the reef, with which the}" finall}^ merge. 



Among the other reefs mentioned by Chamberlin is that of Moody's 

 quarrj', in the fourth ward of the city of Milo'aukee, and in the blufif 

 facing the Menomonee river. This old quarry (Distillery quarr}") is at 

 the foot of Twenty-ninth street. The reef is of the same ty})e as that of 

 the Wauwatosa quarr}^ but the dips are ver}^ stee}), averaging 40 degrees 

 toward east and west and 20 degrees or more southward. A third reef 

 occurs in the grounds of the National Military asylum. This I have 

 not seen, but, according to Chamberlin, it forms a triangle with the other 

 two mentioned. In all cases the reefs constitute mounds, owing to their 

 superior compactness, which permitted resistance to erosion. The older 

 quarries were generally opened in these mounds. Within the triangle 

 made b}^ these three mounds the great limestone quarries of this region 

 are now opened up. Here we find only even bedded limestone, consist- 

 ing of coral and crinoid debris and but sparingly fossiliferous. Regard- 

 ing the fauna of these limestones Chamberlin says :* 



"... Upon the reefs there swarmed a vast variety of life ; . . . upon 

 certain banks or shoal areas there was also great abundance and variety, among 

 which the crinoid family attained unusual prominence ; . . . over areas of 

 submarine sand flats there either was little life present or, from the porous nature 

 of the rock, it has been illy preserved, and . . . over the deep areas that de- 

 posited fine calcareous mud the gigantic Cephalopods held swa^^" 



In the vicinity of Cedarburg several quarries show reef characters. 

 Groth's quarry, near the railroad station, is opened in the flanks of a 

 reef which forms a hill, and is shown in the eastern wall of the older, 

 abandoned portion of the quarr3^ Fossils are numerous in this portion, 

 consisting chiefly of corals, though mollusk shells are also common. 

 The bedding is obsolete here, while stylolite structure is commonly seen. 

 In the western part of the old portion of the quarry bedding is well 

 shown, the strata dipping west and south. Correspondingly, fossils are 

 scarce. The part of the reef exposed is about 30 or 40 feet in thickness, 

 while the length from north to south is perhaps 300 feet. Dolomitiza- 

 tion has gone on to a considerable extent, and in many of the bedded 

 strata the corals have been dissolved out. As a result, cavities, either 

 lined with crystals or empty, abound, these usually marking the former 

 position of a stromatoporoid or other coral. In the new portion of the 



♦Geologj' of Wisconsin, vol. ii, p. 369. 



