314 The Taconic Question Restated. [April 
The rocks of the same series have elsewhere been assigned to 
a still higher horizon. The schistose beds, though principally 
at the summit, are more or less interstratified with the under- 
lying limestones and quartzites of the Lower Taconic, and in 
many places include besides limonite both magnetite and hema- 
tite. Important beds of these latter ores along both borders of 
the triassic series in Pennsylvania, embracing those of the War- 
wick and Jones Mines, of Reading, Boyerstown, Dillsburg, and 
Cornwall, were, by H. D. Rogers, in 1839, referred to the “ middle 
secondary red sandstone” or trias, adjoining them; the peculiar 
characters of these crystalline schists being supposed to be due 
to “the metamorphism of the strata.” In 1858, however, Rogers 
correctly referred them to the horizon of what he called the 
Primal Slates. Lesley, in 1859, while apparently accepting this 
latter view, refers with approval to those who regard these ores 
“as of middle secondary and not of primary age ;” in accordance 
with which opinion the ores of Dillsburg are, by Frazer, in 1876, 
in his Report of the Second Geological Survey of Pennsylvania, 
described as mesozoic, and by McCreath, in his report for 1881, 
are also referred to the same horizon. 
§ 31. The ground upon which J. D. Dana still defends the 
original position of Mather as to the horizon of the Lower 
Taconic crystalline limestones, while at the same time admitting © 
the now unquestioned pre-Trenton and Cambrian age of the 
Graywacke series, is by supposing that the apparent succession 
of eastward-dipping strata in certain sections in this region rep- 
resents their order of deposition, and, consequently, that the 
crystalline limestones are not below the Graywacke, as taught 
by Mather, but above it, and are apparently the altered repre- 
sentative of the Sparry Lime-rock. This, notwithstanding the 
` caution of Emmons, he confounds with the Stockbridge or crys- 
talline limestone of the Lower Taconic, and, therefore, from the 
organic remains, apparently of Ordovician age, found in the 
Sparry Lime-rock at the summit of the Upper Taconic, assigns 
the same age to the Lower Taconic limestone. 
§ 32. In some parts of the great valley of Pennsylvania the 
Cambrian Graywacke or Upper Taconic had been removed from 
the Lower Taconic before the Ordovician age, and now appears 
only in isolated areas. In like manner, the Ordovician limestones 
are represented only by small portions of fossiliferous strata 
