[MaTTHEW] PALÆOZOIC ROCKS OF SOUTHERN NEW BRUNSWICK 93 
for it has yielded no marine remains; it contains rafts and scattered 
trunks of trees, and the plants of its shale beds are of a delicate organiza- 
tion such as might have grown in shallow sheltered pools subject to 
desiccation in the hollows behind sand banks along the river, or possibly, 
on the sea shore. 
Except for the narrow belt of the underlying Bloomsbury volcanics 
and clasties these Dadoxylon sandstones are bordered along their north- 
ern margin by pre-Silurian gneisses, limestones, quartzites and voleanic 
rocks that may have formed the upland, from which some of the tree 
trunks imbedded in these sands, were swept away: these were mingled 
with the more perishable stems of the Equisetaceæ and Psilophyta, 
that grew on the sands themselves. The indications are that land sur- 
faces of an upland existed to the north and east of the tracts over which 
these sands were spread; and that to the south and west of them, the 
finer material brought down by the streams off the upland was swept 
into a comparatively sheltered and quiet bay. Apparently these con- 
ditions were repeated in the two basins containing the principal plant 
remains, but in the third basin only, the marine (?) type of the Dadoxylon 
sandstone, viz., the black silicious fine grained shale was deposited, or 
at least that only is preserved. 
The uniformity of composition ranging only from gray grits to fine 
grained gray shale, more or less heavily charged with carbonaceous 
matter, of the Dadoxylon sandstone, is in strong contrast with the vari- 
able deposits that make up the bulk of the underlying Bloomsbury 
group with which the terrane begins. At the eastern end of the St. 
John basin we recognized the latter first in the low dolerite hills, which 
rise above the gravel terraces to the southwest of Loch Lomond in St. 
John county. 
Tracing this range of isolated volcanic hills westward to the sea 
shore at St. John harbour, we find at their base, red and green shale 
and sandstones, which may be regarded as levigated eruptives, that is 
volcanic ashes that have been dropped into the sea, and there worked 
over by the waves. Similar relations prevail to the west of St. John 
harbour where, however, the volcanic rocks appear in greater force and 
form the hills called Lancaster Heights. Such is the appearance of the 
Bloomsbury group on the north side of the St. John basin of Silurian 
rocks. On the north side of the Lepreau basin the conditions are some- 
what different; here the volcanic rocks have not been found, but red 
beds, sandstones and shales, form the bulk of the Bloomsbury and with 
these is a thin bed of argillaceous limestone; farther west in this basin 
only the red sandstone and shale remain. In the next westward basin, 
that of Beaver harbour, the beds at the base of the Silurian terrane, 
which we regard as the Bloomsbury group are the gray sandstones, 
Sec. IV., 1912. 7. 
