3i8 GEOLOGY OF EASTERN WISCONSIN. 



The thinner beds of this formation furnish an excellent flagging. 

 The compactness and fine grain of some layers fit them for litho- 

 graphic purposes, but they are apt to be marred by occasional small 

 cavities or other flaws. 



Transition Beds. Above the Byron beds, as they are developed 

 in tlie Green Bay peninsula, there lies a series of alternating, coarse 

 and fine grained strata, that are transitionary in character, and mark 

 the passage from the fine textured Byron beds to the coarse textured 

 Coral beds above. They may be briefly described as follows, in 

 descending order: 



Beginning at the base of the Lower Coral beds, there occurs first, a 

 hard, tough, conglomeritic dolomite, of bluish color, mottled with 

 lighter hues, which weathers into creases, rather than pits. It has a 

 close, but uneven texture, and contains some argillaceous partings, 

 and a few cavities. ISTo fossils were seen except in the upper layer, 

 and here only one, not observed elsewhere. This consists of mi- 

 nute, vertical, cylindrical canals, somewhat regularly interspersed 

 through the rock, but separated from each other by several times their 

 own diameter. The general appearance is similar to that which 

 would be given if a small, distant-tubed Syringopora were to be en- 

 tirely removed by solution, leaving only its external cast in the rock. 

 It seemed to be confined to a single layer, which was traced 3,000 feet, 

 for the purpose of securing the dip, which was found at this point — 

 southwest shore of Sturgeon Bay — to be nearly 80 feet per mile, 

 south westward. 



Below this portion, the rock is uniform in texture, close, compact, 

 fine grained, regularly bedded, smooth on the weathered exterior, 

 even in fracture, and is of grayish or white color. JSTo fossils were 

 observed in this portion. 



Below this, there are thick, heavy, granular beds of coarse, crystal- 

 line texture, and irregular hardness, in general, quite similar to the 

 Lower Coral beds in lithological characters, but containing few or 

 no fossils. The observed thickness of these, taken together, is about 

 30 feet. 



Below this, there is more or less of alternation between the thin 

 bedded, compact rock, that characterizes the Byron beds below, and 

 the thick-bedded, coarse-grained rocks that represent the formations 

 above. The conglomeritic layer is the only one that is not, in its na- 

 ture, allied either to the Lower Coral beds above, or to the Byron 

 beds below. 



