ON THE TACONIC AND CAMBRIAN SYSTEMS. 49 



mediary gToups to overlying formations, the ;ige of which was previously well known, we 

 hat c an i\ ed gradatim, and without hj pothesis, ai the apparently true base of the zoological 

 series in Europe. Ii is right, therefore, that I should announce thai the conventional line 

 which \\;is set up 111 the map of the Silurian region, between the Lower Silurian and Caru- 

 brian rocks, and which has been adopted by Mr. Greenough, has no longer any reference 

 to strata identified by distinguishing organic remains: for the same fossils are found in 

 strata on each side of that demarcation. Such lines of division, however, when viewed 

 as of local phenomena, are notwithstanding highly useful, both as indicating changes 

 of lithological character, great lines of disruption, and lower divisons of the same palaeozoic 

 group. In short, all researches up to this day have led to the belief that the Lower Silu- 

 rian fossils were the earliest created forms; and thai this protozoic type prevailed during 

 thai vasi succession of time which was occupied in the accumulation of all the older slaty 

 rocks, until the Upper Silurian period, when new creatures were called into existence, 

 and when the earlier forms diminished, and were succeeded by a profusion of chambered 

 shells which so abundantly characterize that epoch. This is, I trust, a good step gained. 

 To establish upon sound data the true theory of organic succcession in the oldest forms of 

 life, is surely important ; and we ought to rejoice that British islands have afforded us the 

 means systematically to work out the question." 



It is needless to remark in this place upon the announcement of the abandonment of the 

 Cambrian system. Suffice it to say that the fact is explicitly declared, and the society is 

 congratulated that a step is gained in geology by the final settlement of an important 

 question ; and were it not for a single fact, the writer would freely acquiesce in the deci- 

 sion, so far as British rocks are concerned. This fact is found in the existence of peculiar 

 fossils on both sides of the Atlantic, which, so far as discoveries have yet been made, are 

 confined to the slates of the Cambrian and Taconic system ; and now the great object of 

 the writer is to show that the above question has not been settled right, or according to 

 facts ; or, in other words, that the Taconic rocks are not the Hudson river slates and shales 

 in an altered state, or that all the Cambrian rocks are not Lower Silurian. 



kj 3. Relations and characters of the Hudson river rocks, embracing also rra 



CHAMPLAIN DIVISION OF THE NEW-YORK SYSTEM. 



Before proceeding to that part of my work in which I design to describe the members of 

 the Taconic system, it will be useful and proper to lay before the reader a brief view of the 

 Champlain division of the New-York system, as it embraces what have been denominated 

 the Hudson river locks ; for it is by a correct knowledge of these masses, that we obtain 

 the necessary facts upon which to decide the question whether we have a Taconic system or 

 not. 



In 1838, in my report for that year, I stated that the Potsdam sandstone was the oldest 

 sedimentary rock in Potsdam and its vicinity, and that no rock intervened between il and 

 [Agricultural Report.] 7 



