Sketch of W. W. Ma titer. —Hitchcock. 5 
interpretation for certain formations in this district not ac- 
cepted by any other one of the board of geologists except in 
part by Vanuxem. These rocks consist of a series of great 
thickness, sandstone, limestone, and slate, to which Emmons 
gave the name of Taconic S3^stem, and supposed them to 
underlie the Potsdam sandstone, then esteemed as the base of 
the Silurian system. Inasmuch as these rocks did not occur 
in the second district, Emmons could not legitimately des- 
cribe them in his official report except cursorily; nor could 
his views be properly illustrated upon the general geological 
map compiled from the reports of all the geologists. Hence he 
was compelled to state his views in a volume prepared later 
upon Agriculture, and to draw his illustrations largely from 
the adjoining states of Massachusetts and Vermont. This di- 
vergence of views led to the Taconic controversy — a discussion 
that became very bitter between its chief disputants — com- 
parable in intensity and duration to the similar conflict in 
England between Sedgwick and Murchison over the Cambrian 
and Silurian. In fact the principles involved were identical 
upon the two continents, ('onnected with the stratigraphical 
discussion arose the subject of raetamorphism, which was 
unnecessarily controverted by Emmons and advocated by 
Mather. 
On these subjects Mather held : (1) The " Taconic rocks are 
the same in age with those of the Champlain Divisiop, but 
modified by metamorphic agency and the intrusion of 
plutonic rocks." p. 438. (2) The limestones that are 
frequently crj^stalline white and variegated marbles, talcose 
slates and quartz rocks of Dutchess, Putnam, Westchester, 
and New York counties are metamorphic rocks. They were 
originally "the rocks of the Champlain Division, but much 
more altered and modified by metamorphic agency than tlie 
Taconic rocks." page 464. (3) The Primary [Archean] 
rocks are extensively developed in the highlands of the Hud- 
son, in New York, Westchester, Putnam, southern part of 
Dutchess, parts of Orange and Rockland counties, and Staten 
island. Tlie kinds of ores and rocks correspond with tliose in 
the northwest part of the first district, in the Adirondack re- 
gion. 
The views of Mather on all these points would not essen- 
tially vary from those recently presented by professor James 
