Septembbh 14, 1900.] 



SCIENCE. 



407 



The fauna alone shows that during the earlier 

 part of the period of their deposition the east- 

 ern province was more completely secluded 

 from the interior sea than during its later 

 stages. The Canadian geologists have ex- 

 pressed the probability that the 7000 feet of 

 arenaceous sediments comprising the Gasp6 

 sandstone may represent the major part of all 

 subsequent Devonic deposition in that region. 



Note B. — The fauna of the Helderbergian 

 passes upward into the deposits of the Oriskany 

 without abrupt or profound change. Its species 

 perdure, but progress and definition are evinced 

 in the later fauna by the introduction of many 

 distinct types. 



The prevailing conception of the Oriskany 

 as a purely arenaceous deposit and which 

 figures largely throughout this argument is 

 one which needs readjustment. The normal 

 fauna of the Oriskany of New York is that of 

 the calcareous beds of the eastern part of the 

 basin. These beds always contain a considera- 

 ble content of silica in the form of sand, but 

 they are clearly the deeper water deposits of 

 which the sandstone beds of the typical Oris- 

 kany section and the intermediate thin bands 

 of altered sandstone (quartzite) are the shallow 

 water shore-line deposits. The sandy layers 

 of the Oriskany onlj' share the fauna of the 

 calcareous beds, and it is quite clear that their 

 species have been derived from the deeper 

 water centers of dispersion largely through 

 mechanical agency. It is therefore not compe- 

 tent to argue a lower calcareous Oriskany and 

 an upper arenaceous Oriskany, as, in New 

 York, at least, there is but one Oriskany fauna, 

 and the formation is not divisible into facies 

 exoept geographically. 



The foregoing notes indicate that the argu- 

 ment cited is built upon the sand. Neverthe- 

 less it is throughout that which served de Ver- 

 neuil and Murchison above fifty years ago and 

 through that agency produced its effect upon 

 Hall's correlation of the Oriskany and Lower 

 Helderberg. It is that argument too with no 

 additions, summed up in the statement that 

 Siluric time was closed with a general world- 

 wide crustal elevation initiating rapid base- 

 leveling and the accumulation of sandy deposits 



at the opening of the Devonic in all countries. 

 To the recrudescence of this ancient doctrine 

 the labors of Kayser, Freeh, Tschernyschew 

 and other European geologists upon the cal- 

 careous facies of the earliest Devonian in the 

 Harz, Westphalia, Bohemia and the Urals af- 

 ford no balm. The old hypothesis of cycles of 

 sedimentation loses force when applied simul- 

 taneously to every part of the earth's surface, 

 and cycles of sedimentation are not a basis of 

 geologic classification save as some element 

 therein indicates widespread orographic de- 

 rangement. The argument as here constructed 

 seems to be as follows : The grand event which 

 terminated the Siluric was the universal eleva- 

 tion of the land, the erosion of which supplied 

 the materials for the sandy sediments of the 

 opening stages of the Devonic. This opening 

 Devonic stage in the marine succession is im- 

 pregnated with species of Oriskany type ; ' the 

 Lower Helderberg is therefore proven to belong 

 to the typical Silurian system of the American 

 Continent ' {op. cit., p. 26). Both premises 

 limp and the conclusion falls. The deposit'on 

 of sandy sediment was not contemporaneous -n 

 the early Devonic, but, however widespread, it 

 may have been upon the epicontinental plateau, 

 calcareous sediments of contemporary origin 

 must have been present in the greater and less 

 disturbed depths, retaining some of the pre- 

 existing types, but showing freely the pro- 

 gressed and differentiated types of the new era. 

 These relations of coeval faunas can be deter- 

 mined only upon the most careful analysis of 

 organic content, and such analysis has cogently 

 shown the intimate afiinity of the Helderbergian 

 with the calcareous Oriskany of which it is the 

 immediate and purest calcareous predecessor in 

 the vertical series. As in the Gaspe succession, 

 so in New York, the species of Helderbergian 

 time, notably unlike in the two separated prov- 

 inces, pass, in each, into association with those 

 of the Oriskany when by transgressing sedi- 

 mentation and freer intercourse between the 

 provinces a consequent commonalty of species 

 was effected. 



The succession in the Gaspe peninsula like 

 that of the basins of Bohemia an«l the Urals 

 again declares the ultimate and final authority 

 of the fauna, its variations, progression and 



