544 



PROCEEDINGS OF THE ALBUQUERQUE MEETING 



cline was the Anderdon, and on this came to rest the Dundee (see diagram, 

 figure 1). In the southwestward extension of this same fold the bed exposed 

 at the top of the truncated anticline was the Sylvania, the axis of the anticline 

 here having crossed to the south of the line of overlap — that is, the shoreline 

 at the end of Anderdon time. At this point the Dundee came to rest directly 

 on the Sylvania, remnants of it being still visible in intimate association with 

 the Sylvania. This intimate association of the two caused Rominger to mis- 

 take the Sylvania for the Oriskany. South of this axis the Dundee came to 

 rest again on the Lucas beds, as shown in several quarries in the vicinity of 

 Sylvania, Ohio. This section formed the southern flank of the Anderdon-Toll- 

 pit anticline. Since the line of overlap of the Amherstburg over the Ander- 

 don — that is, the shoreline at the end of Anderdon time — curves more to the 

 south than does the axis of the anticline (extending from the Gibraltar quarry 

 and the region south of Amherstburg through the Woolmith quarry and thence 

 curving south to the Silica and Webster quarries near Sylvania), it Is evident 

 that the resultant outcrops will be quite varied. 



POSSIBLE ECONOMIC VALUE 



Incidentally it may be remarked that these anticlines may have an economic 

 value, since all the lower strata are involved, and favorable conditions for the 

 storage of oil and gas thus created. The fact that these anticlinals could 

 have been located only with the help of paleontology seems, in view of what is 

 known of the connection of oil and gas with such structures, an interesting 

 illustration of the practical value of the study of the fossils. 



Peoof of the Lower Devonic Hiatus 



The foregoing discussion has made clear that a hiatus of considerable magni- 

 tude exists between the Monroe beds and the overlying Dundee limestone, the 

 approximate equivalent of the Onondaga limestone of New York. At the salt 

 shaft this limestone rests on 189 feet of Lucas dolomite. At the Sibley and 

 the Anderdon quarries it rests on Anderdon limestone. Between the two on 

 Grosse isle and Stony island lower Lucas is present ; at the Gibraltar and 

 Woolmith quarries the Dundee, now removed, formerly rested on less than a 

 hundred feet of Lucas. Three to 4 miles southeast from the latter locality 

 the Dundee rests on the Sylvania, and fossils of the former occur in the re- 

 worlced upper portion of the latter. Near the Silica and Webster quarries and 

 at the S. K. Cooper quarry, near Sylvania, Ohio, the Dundee rests again on lower 

 Lucas. Further southea.st in Ohio the Dundee (Columbus) rests on various 

 members of the Lower Monroe," while at Buffalo, New. York, the Onondaga 

 rests on the lower 7 feet of the Bullhead or Akron liuie.stone, the probable 

 equivalent of the Amherstburg bed of Michigan and the Cobleskill of eastern 



° "Relative to the lower ,S5 or 40 feet of the Columhus limestone, permit me to add a 

 word : In central Ohio the dividing line between this 'brown saccharoidal magneslan 

 limestone' and the underlying Monroe formation, with Its banded compact drab lime- 

 stone, is very distinct. In fact, It is an unconformity [dlsconformlty], and at many 

 places the lower portion of the hrown limestone (Columbus) Is a real basal conglom- 

 erate. From this 40 feet of brown limestone I have collected a rather scanty Columbus 

 limestone fauna, even In the basal layers. At Sandusky and vicinity the unconformity 

 [disconformity] is also evident. Uere the upper part of the Monroe formation carries a 



