Two New Species of Fossil Footmarks. 57 



distanceyigainst which the east end of Holyoke abuts, with only 

 a narrow/ space between. It is obvious then, that this locality 

 must have been the north shore of an estuary, opening southerly, 

 and extending to what is now Long Island Sound. That it was 

 salt-water is evident from the occurrence of fucoids in the same 

 basin, a few miles south. Now we know that the current through 

 this estuary was either north or south, for the ripple marks have 

 an east and west direction , and in size they correspond with 

 those made by the waters of the Connecticut on the sand in the 

 same region. The direction of that stream also is south ; and 

 some have thought that the floods of that stream may have 

 brought in the sand which filled the tracks. But the locality 

 must have been defended from a northerly current by Mount 

 Holyoke, whose elevation doubtless formed the shore on which 

 the animals trod. Indeed, it would be exposed to no current 

 that I can conceive of, sufficiently powerful to move such coarse 

 materials, except the waves and tides from the south. And yet, 

 a deposit at least six inches thick of coarse sand, was brought in 

 over the tracks. It seems difficult to conceive how any river 

 floods should have raised the waters of an estuary enough for this 

 purpose ; and more difficult to show how these coarse materials 

 could have been thus brought over this spot. I have hence been 

 rather inclined to suppose that they were silted in by the waves 

 and the tides: — not the daily tides, but the spring tides. Sup- 

 pose the animals walked along the shore during neap tide, and 

 that no rain fell till the return of spring tide. By that time the 

 mud might have become so indurated, that even such coarse ma- 

 terials might have been brought in by moderate waves, without 

 erasing the impressions. It might be also that the river, which 

 doubtless flowed into this estuary, answering to the present Con- 

 necticut, was at the same time swollen ; and perhaps also we 

 must resort to the supposition of a subsidence of the locality 

 an occurrence not uncommon during igneous eruptions: and we 

 know from other circumstances, that the tracks were made about 

 the same period in which Holyoke was erupted. We have evi- 

 dence also that this period, including some precursory outburst 

 of the igneous matter, was quite long. 



Should time and health permit, I hope to send another com- 

 munication ere long, describing other new species ol tracks in 

 the Connecticut valley. I have no others, however, that are so 

 remarkable as the largo one herein described. This, indeed, 

 ^eems to eclipse that of the Br onto mm (Ornithoidichnites) 

 ghaut eum, figured in the Journal of Science for 1S3G, being 

 even of greater dimensions. I had thought that we had reached 

 nearly the end of this mcient volume ; but it may be, that many 

 new chapters will yet be brought to light, when it tony leave 

 shall be still farther opened. 



scoNu Series, Vol. IV, No. 10.- July, 1847. 8 



