398 J. D. Dana—Taconic Rocks and Stratigraphy. 
and limestone, and preéminently in the limestone which occurs 
adjoining the schist at intervals for long distances in western 
Berkshire (in Lanesborough, Richmond, and West Stockbridge 
and less abundantly in other towns), as’ well as in Vermont 
to the north and Connecticut and New York to the south—the 
limonite beds attesting to it. This is good evidence that the 
beds are natural in sequence; that there has been no great 
lateral move by a thrust-fault over the region of Berkshire and 
eastern New York, disturbing the order of stratification. 
2. The true stratification is not disguised by foliation, or slaty 
cleavage, or other effects of pressure.—Questions as to slaty cleav- 
age, foliation, schistosity, are not a source of serious difficulty 
in the Taconic region. If the rocks were all slates, all mica 
schist, all hornblende schist, or all limestone, that is, were wholly 
of one kind, the uncertainties as to bedding or not might be 
well-nigh insurmountable. But where the three kinds are 
together in alternating layers or strata, the doubts disappear, 
for there is then distinct stratification between layers or strata 
of different kinds in constitution, and the study of it is like the 
study of stratified rocks in non-metamorphic regions. If in 
such cases the schistosity of a schist is parallel to the planes of 
junction between the layers or strata of the different kinds, its 
planes are essentially those of bedding whatever their origin; 
and this is eminently manifest in Berkshire where one of the 
rocks is limestone. Alternation in strata or layers of different 
kinds of rocks cannot be a result of pressure. The principle 
presented is as true for Archean rocks as for any others and 
affords a criterion which is of great value in their investigation. 
For the reasons stated, the Taconic region is as much a 
region of stratified rocks as that of western New York. It has 
its strata of limestones, sandstone (quartzyte) and schist, the 
study of whose positions is stratigraphical study, far outside of 
microscopic investigation, though deriving great aid from such — 
investigation as regards the constitution of the beds, metamor- 
phie changes, and other points. The planes of junction 
between the strata are open to observation. And it is wonder- 
ful how very generally the planes of lamination in the schist 
correspond in position with these planes of junction. It is so 
general that the geologist of the region comes naturally to the 
opinion that it is exceptional for foliation to be any other than 
lamination conformable to the bedding. Stratification in the 
region stands out with the distinctness that characterizes ordin- 
ary regions of stratified rocks, and the anxiousand sceptical 
petrographer has no occasion for his doubts, or for his expecta- 
tion of settling all such cases with the microscope. 
in many places, moreover, the strata are piled to mountain 
height while still nearly horizontal in the position of the beds. 
Such nearly horizontal Jamination is not due to pressure attend- 
