LOWER SILURIAN SYSTEM OF EASTERN MONTGOMERY CO. 425, 
above designation. Three miles north of Amsterdam it is said to. 
be “ quite pure, compact and durable.”? 
In the Second annual report by Vanuxem the Trenton is definitely 
spoken of as “ Trenton limestone ” with the statement that “ South 
of the Mohawk the Trenton limestone both in Herkimer and Mont- 
gomery counties rarely exceeds a thickness of Io feet nor much 
beyond that thickness in any part of the latter county.’* The 
faunal character of the rock is stated as follows: 
This limestone is readily distinguished from all the other rocks 
by the numerous individuals of the Leptaena alternata [Ra fines - 
quina alternata (Con.) Hall and Clarke], Delthyris striatula 
[fOrthis (Dalmanella)testudinaria Dal.?], Orthoceras 
striatum, Bellerophon apertus, Favosites , Calymene blumen- 
bachii [C. callicephala Green], Cryptolithus tessellatus. 
[Trinucleus concentricus Eaton], Isotelus gigas [As- 
aphus platycephalus Stokes] and cyclops [same as pre- 
ceding] (p. 283). P 
In the Fourth annual report Vanuxem says that on the Mohawk 
river the Trenton is in no place 30 feet in thickness,’ but again 
“On the Mohawk its thickness rarely exceeds 30 feet” (p. 371). 
In his final report this statement is repeated with the addition that 
“it is not so thick at the east as at the west end.’4 Here also he 
says that “the gray variety of limestone does not appear upon the 
Mohawk.” 
In Mather’s reports the occurrence of the Trenton in Schenec- 
tady county near Amsterdam is several times mentioned specially 
in the final report,® and in this report a section is given made by 
Cadet T. Seymour at “ Marlit & Denham’s quarries, near Hoff- 
’ 
man ferry” which foots up 20 feet, 10 inches (p. 400). This may 
be the Weatherwax quarries of the present paper. 
In the 13th annual report (1893) the Trenton is said to comprise 
three principal members, a “thick bedded, coarse grained, light 
colored crinoidal limestone. . . underlaid by a series of thin 
bedded, dark limestones, with more or less intercalated black 
shale. . . Then there is a very massive, dark, coarse limestone 
which begins as a basal series near the Mohawk in the eastern 
1Zoc. cit. Assembly doc. no. 161, p. 163, 164. 
2Loc. cit. Assembly doc. no. 200, p. 275. 
8Zoc. cit. Assembly doc. no. 50, p. 365. 
*Geology of New York, pt 3, p. 49. 
5Geology of New York, pt 1, p. 397, 398. 
