504 GEOLOGY OF OHIO. 



same direction. The point where the Erie and Waverly strata come 

 into juxtaposition is not, however, along the shore of the Waverly sea, 

 but far to the eastward of the littoral deposits. The two sets of rocks 

 were formed then by different but occasionally interblended seas. The 

 line of strike measurably conforms to the shore line in the Waverly. 

 Thus the plane of 1,000 feet elevation intersects the Moot's run horizon 

 in Licking county and some distance west of Portsmouth in southern 

 Ohio, while at Lodi the same horizon seems nearly at 825 feet probably, 

 throwing the line of intersection further toward the west. There has not 

 been any considerable change of level since the sediments were deposited 

 beyond the gradual sinking of the centre of the basin. It is evident 

 that the Devonian basin in New York and that of the Carboniferous in 

 Ohio are not coincident nor have their movements followed the same 

 rh)4hm." 



"When the strata which constitute the Chemung in New York were 

 forming, what was going on in Ohio?" 



"There seems to have been a pretty general uniformity in conditions 

 during the Hamilton period over the entire area considered — indeed a 

 much more extensive one. The change which made the sediments of 

 New York littoral sands and induced a modification of fauna may not 

 have been felt at once in distant areas in Ohio. The undisturbed seas in 

 Ohio may have been concealing a fauna more closely allied to the Ham- 

 ilton, while the oscillation along the western border of the Chemung area 

 may have once and again thrown a great apron of its own sediments over 

 Hamilton beds, only to be in turn covered by a similar apron from the 

 Ohio beds." 



"What, indeed, is to prevent us from believing that when the early 

 fluctuation of the northeastern part of this area was bringing more and 

 more of the Silurian shore-line within its own erosive power and accumu- 

 lating coarse detrital material in great masses, the weed} r sea of the 

 Hamilton continued unaltered in Ohio. Sand}- bottom, stormy waves 

 and unaccustomed conditions of all kinds must have their effect on the 

 organization of the fauna and, if accepted ideas of the causes of evolu- 

 lution are correct, a sudden change would be seen in a faunal develop- 

 ment more or less forced, one-sided, and local." 



"Great variet3 r within narrow groups is the rule under such condi- 

 tions. Just as the sudden formation of a prairie out of a morass develops 

 hundreds of species in a few genera, so, in this case, such groups as could 

 cope sucessfully with the new conditions would expand, while others dis- 

 appear. As the agitation extended westward the plot thickens. Some- 

 where on the western part of our area we should expect to find strata 

 strangely interblended, just as a player in cutting and shuffling a pack 

 thrusts the edges of the cards between each other. Here we should find 

 a stratum marking the return of the former conditions." 



"Such a state of things as we have supposed would explain the con- 

 ditions in northern Ohio in the period before the Berea grit, which put 



