396 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



uplift, — such agency being sufficient to produce all the observed phe- 

 nomena, and the effects diminishing westwards from the central line 

 of disturbance. No other agency is known to me, although hinted 

 at by American geologists. 



13. It is a remarkable fact that brine-springs exist in considerable 

 quantity in the Middle stage of the Silurian system, a group or two 

 below the Onondaga-salt -springs of the Upper stage, and three 

 palaeozoic systems below any salt-deposits in Europe. 



14. That the form and direction of the five great Canadian lakes 

 are not due originally and mainly to the passage of loaded waters 

 over their site, but that they follow the outcrops of their containing 

 sedimentary rocks, — changes in shape and size having, nevertheless, 

 occurred since. 



15. The contours of the valley of the St. Lawrence generally (to 

 which much of New York belongs), and its increasing elevation south- 

 westwards, inland from Montreal, are due to the successive altitudes 

 assumed westward, in slopes and plateaux, by the Silurian and Devo- 

 nian strata, the lowest or most ancient being on the east. This is 

 beautifully evidenced in the rocks forming the basins of the great 

 Canadian lakes. 



16. That some of the groups, during and after deposition, were 

 sub-atmospheric, presenting the conditions of dry land and shallow 

 waters for long and varying periods, — and that, together with the 

 marine life they supported, they enjoyed the influences of the sun 

 and other meteorological agencies. This is indicated by animal 

 tracks, sun-cracks on ancient shores, the short ripple-marks of a 

 chopped sea, impressions of reeds waving in running water, and by 

 the presence of bog-iron-ore. This is conformable with what took 

 place in the carboniferous, permian, triassic, liassic, oolitic, wealden, 

 and later periods. Denudations also occurred to most of the groups 

 to a large extent. 



17. That in New York, as elsewhere, there is an intimate con- 

 nexion between fossils and their sediment or habitat. The calcareo- 

 colous animals are always found in limestone more or less pure, 

 and the arenicolous in sandstone more or less pure, — with exceptions, 

 such as usually happen with respect to locomotive animals. The 

 calcareocolous are everywhere the most numerous. It is true that 

 molluscs are the principal agents in the deposition of calcareous sea- 

 bottoms ; but these latter greatly favour afterwards the multiplication 

 of individuals. 



18. That the iron-ore which we so frequently see investing inverte- 

 brate remains had access to them after their death and sepulture. 



19. Every group, as established by the State Geologists of New 

 York, is a distinct centre of life, — a separate realm or community of 

 animated beings, which may be called epochal, so marked are the 

 differences. 



The majority of these existences always perished at the end of 

 the group when certain deposits ceased, because the new sediment, 

 with its new and peculiar flora (and for other reasons), was only 

 able to nourish a few, if any, of the old molluscs. 



