BIGSBY — PALAEOZOIC BASIN OF NEW YORK. 441 



rocks in that State. These strata are, therefore, the offspring of 

 quiet times, not excepting Oneida Conglomerate, when out of a 

 certain disturbed district, and when acted on by currents only. To 

 this conformability in the several important sections with which I 

 am acquainted, I offer personal testimony. 



2. This rest from plutonic interference is indicated by the usual, 

 and often extreme, fineness of the deposit, and by the small pro- 

 portion of conglomerate or breccia in these ever-varying strata ; 

 coarse materials, indeed, are often due to surf-action, or to currents 

 urged on by winds. 



3. It is indicated by the very gradual mineral passage from one 

 stratum to another during the palaeozoic age. 



4. It is indicated by the fact that fossils are in common, in many 

 coterminous strata, for certain thicknesses. 



This proposition is adopted by many leading geologists in America. 

 James Hall, in his Official Report, p. 20, says, "From the absence 

 of all extensive disturbances of the strata, we are enabled to trace an 

 uninterrupted series from the Potsdam Sandstone to the Old Red." 



In his * Palaeontology' (vol. i. p. xv.), the same author regards "the 

 entire succession as forming a series intimately linked together by 

 the nature of its organic contents, and showing no important changes 

 till we arrive at the Old Red Sandstone." Again (Sill. Journ. n. s. 

 vii. 49), James Hall makes the decisive statement, " During all the 

 time of its deposition [the palaeozoic formation in North America], 

 the surface was free from great disturbances." 



Prof. Emmons, one of the State-geologists (Rep. p. 99), remarks 

 that, " In the whole space, such is the order and regularity in the 

 succession [of the New York palaeozoic rocks], that we meet with 

 no unconformable masses, nor sudden and abrupt passages from one 

 group or series of rocks to another. There is a gradual sequence 

 or transition from one mass to another." 



Sir William Logan (Canad. Journ. 1854, p. 1), speaking of the 

 New York strata continued into Canada, writes : " These various 

 formations are a set of close-fitting, conformable sheets, intersected 

 by the general surface of the country." 



De Verneuil (Bull. Soc. Geol. de France, 2 ser. iv. 684) says : 

 "During the whole period in which the palaeozoic ' terrain' was 

 being deposited in North America, the earth was free from great 

 perturbations." 



Dr. Fitton has informed me that, after careful personal examina- 

 tion of the palaeozoic rocks of Wales, in company with our late Pre- 

 sident, Daniel Sharpe, he is of opinion that the whole belong to the 

 same grand epoch, and may be called Cambrian or Silurian at plea- 

 sure, according as the observer begins at the bottom or at the top 

 of the series. 



Sir Roderick Murchison, in his ' Silurian System,' gives proof 

 upon proof of the gradual passage of nearly all the Welsh deposits 

 into each other, together with five distinct instances (and perhaps 

 more) of the Lower Silurian being continuous into the Longmynd 

 rocks (pp. 256, 352). 



