EARLE, INTERBEDDED IRON ORE DEPOSITS II9 



of sand and pebbles been fairly inaugurated, when the work was brought to a 

 sudden close by a deepening of the waters, or a change of sediments. The 

 enfeebled curi'ents were now enabled to carry only the finest sands and clays, 

 the materials of which formed the innumerable layers of shale. The later 

 condition seems to have predominated throughout the entire Clinton epoch, 

 but the frequent occurrence of sandstone marks intervals of time and less often 

 repeated, the conditions favorable for the deposition of sands and clays gave 

 place to conditions favorable to the deposition of limestone. The last named 

 conditions point to the clearing of the waters, and probably also the deepening 

 of the sea. The thinness of the individual limestone l)eds would indicate that 

 the conditions favorable for the deposition were of short duration. Yet, at 

 the same time, the extended area over which they often occur shows that the 

 <*onditi()ns were widespread, and not confined to certain special localities. In 

 the entire series of Clinton rocks, from the beginning to the end, we here see 

 no evidence of sudden upheavals or tilting of strata. The character of the 

 sediment points only to general oscillations of the sea floor, many times re- 

 peated." 



At the close of the Clinton, no marked changes took place till the close 

 or near the close of the Niagaran period ; then came a gentle uplift, as 

 shown by the erosional unconformities. This emergence continued well 

 into the Middle Silurian. Before the close of the Silurian period, two 

 more periods of elevation have been recorded. 



The layers of sediment that formed a portion of the epicontinental 

 shelf at the close of the Clinton era thus emerged from their original 

 position and at the close of the Niagaran became a part of the coastal 

 plain, the layers of the Clinton foniiation outcropping and thus placing 

 their catch basins in a position favorable for the easy penetration of me- 

 teoric waters charged with iron-bearing solutions. 



Tlie following correlation table has been taken from Professor Grabau's 

 work (128, p. 87) : 



Mluric: Upper or Monroan Hiatus and disconformity 



Akron dolomite 

 Bertie waterlime 



Hiatus and disconformity 

 Middle or Salinan Hiatus and disconformity 



Salina Camillus 



Syracuse 



Vernon 



Pittsford 



