The Taconic or Loxt'er Cambrian. — Winchell. 
303 
3. Quartzyte (gneis- 
sic), limestone, schist, 
succeeding each oth- 
er (upward?). Specu- 
lar hematite in the 
limestone, magnetite 
in the schists. 
4. Older schists, non- 
conformable below 
No. 3. 
3. Cambri an 1 i m e- 
stone, with schists 
and quartzyte. 
3. Quartzyte, 1 i m e- 
stone, schist, in as- 
cending order. Ore 
horizon in the lime- 
stone, just above the 
quartzyte. 
4. Older crysta 1 1 i n e 
rocks, non-conforma- 
bl(.' below No. 3. 
Taking the foregoing in reverse order the great historic and 
geologic features involved in the table may be recorded as 
follows : 
4. There was, according to available evidence, at least in 
the Adirondacks and the Taconic area, an Archean complex 
of schists and gneiss, associated, at least in some parts of 
Vermont, with greenish and sericitic schists. These consti- 
tuted portions of the earliest land area or protaxes of the 
eastern part of the United States.* 
3. In the Taconic and Adirondack areas the rocks were 
formed in crystalline condition prior to the deposition of an- 
other series which is now sub-crystalline, or holo-crystalline, 
and they furnished fragmental materials to this second series. 
This second series is what has long been known as the Ta- 
conic, or later as the Lower Cambrian, and its thickness in 
Vermont, according to Mr. Walcott, is not less than 15,000 feet. 
It embraces quartzyte, marble, dark gneisses and soft, often 
graphitic, schists; and in the limestones, near their base, are 
often found large and valuable deposits of hematite. These 
rocks have furnished many new and important data of crys- 
tallization, many new mineral species and manj^ problems in 
petrography. They hold in America nearly all the ore de- 
posits of economic value older than the Lower Silurian. 
2. The next step, in the table of events, that marked the 
age of the Taconic, or Lower Cambrian, was the great irrup- 
tive catastrophe which gave origin to the basic gabbros and 
allied rocks. On all hands it is agreed that this was accom- 
panied by the folding and faulting of the Taconic sediments, 
by the crystallization of the concerned strata, by the effusive 
commingling, in some parts at least, of volcanic debris with 
*I)axa. Hull. Geol. Soc. Am., vol. i, p. .36, 1890. 
