Po)<t-Arc]i(('Un A(i( of W hit<: Lunr-StoHt^x. — 2\\i.s{))i. 169 
The blue limestones are almost wholl}' free from eruptives and 
granite is never present. Taking these facts in connection witli 
the disturbed areas as shown b}' the topograph}', the presence of 
granite in the white limestone and its absence from the blue is as 
easily accounted for as the fact that the white limestone occupies 
areas of great disturbance, while the blue area is comparatively 
undisturbed. 
?). The transition of the ])lue limestone into the white. 
The writer regards this gradation as absolute proof of the 
s3'nchronous horizon of these two limestones and that this fact 
alone is sufficient to establish the point at issue even were there 
no other confirmatory' facts. 
That this gradation or transition actually exists no one will 
doubt if once he visits the localities in question, (a) Breccias in 
the white limestone are not always readily observable, but localities 
are found where great masses of limestone are made up entirely 
of angular fragments. The interstitial matter is coarseh' crystal- 
line with scales of graphite. The angular fragments are bleached 
and some have a distinctly crystalline structure with scales of 
graphite and cloudy aggregations of the same mineral. In some, 
the angular outline of the original fragment is plainly ol)serval)le. 
J)ut near the center the crystalline structure is lost and the core is 
a rounded, comparatively unchanged mass. Were it not for the 
aliundance and variety of these breccias one might regard them as 
a kind of concretion. 
(1).) The breccias in the blue limestones, like those in the white, 
are found near the boundarj' line, or are. rather, the actual 
])oundary line; the white limestones being found on one side and 
the blue on the other. The bi'eccias are filled interstitially with 
crystalline graphitic limestones. The fragments themselves, while 
as dark as tlie ))lue limestone, have occasional scales of graphite. 
The degree of alteration depends upon the size of the fragment. 
The boundary line between the blue and. white, when they ap- 
proach each other, is either brecciated rock or a line of easy 
gradation as noted under H (d). (c)^The presence of graphite 
and fossils in the blue limestone and in the sandstone, 
standing as isolated facts, do, as Prof. Dana says, have but 
doubtful significance, but this particular case stands as fol- 
lows: — The fossils show these rocks to be among the oldest of 
fosiliferous rocks and thus more liable to metamorphic action; the 
