44 L. W. BAILEY ON THE PHYSIOGRAPHY, ETC. 



The fossiliferous limestones of both of these sections have been alike referred, by Mr. 

 Billings and Mr. Ami, to the Lower Helderberg formation, and of this reference the variety 

 and perfection of the fossils leaA^es no doubt. But while, in the Maine reports, the asso- 

 ciated beds are described and represented as Devonian, the facts here given would seem 

 to indicate that these also are rather to be regarded as Silurian. It is true that the Oriskauy 

 formation, to which these beds have been referred, is variously regarded as pertaining to 

 either or both of these systems, but in the sandstones of the Aroostook, described above, 

 not even Oriskany species have been found to occur, the faciès of the shells being rather 

 that of the Niagara formation. Moreover, if, as the facts both here and elsewhere indicate, 

 the fossiliferous sandstones are succeeded by the great masses of calcareous slate, which 

 spread so widely over northern Maine and the adjacent portions of Quebec and New 

 Brunswick, and which, at many points, contain Silurian fossils, a considerable thickness 

 of strata must intervene between the fossiliferous limestones and the real summit of the 

 Silurian system in this region. It may be added that an almost exact parallel to the suc- 

 cession as here given in Aroostook County, Maine, is repeated, with abundant fossils, on 

 the shores of Lake Temiscouata, and will form the subject of a forthcoming Report in 

 the volumes of the G-eological Survey. 



By the above observations it is by no means intended to indicate that no Devonian, or 

 at least no Oriskany beds are to be found in northern Maine. On the contrary, the exist- 

 ence of the latter would appear to have been well established by the occurrence of charac- 

 teristic fossils at a variety of points, and similar beds have recently been discovered by 

 Mr. "W. Mclnnes, in the Upper Tobique region, in New Brunswick. But that much of what 

 has been so regarded in Maine is really Silurian, seems, from the observations here given, 

 to be placed beyond reasonable doubt. The only beds seen by the writer within the dis- 

 trict visited which are certainly newer than Silurian, are a series of soft brownish-red 

 sandstones and conglomerates, which may be seen three or four miles from Presquile, 

 on the road to Ashland, and which repose, with little inclination, upon the highly-tilted 

 Silurian slates, elsewhere abundantly exposed along the same highway. These have also 

 been regarded, in the Maine reports, as Devonian, but it is quite as probable that they are 

 Lower Carboniferous, bearing, as they do, the closest resemblance to the beds of this age 

 seen in the Tobique valley and elsewhere in the Province of New Brunswick. 



It is much to be desired that a thorough resurvey of the County of Aroostook should 

 be made, and more ample collections be obtained and examined from the numerous and 

 exceptionally rich fossiliferous strata which it contains. 



