[MATTHEW] A BACKWARD STEP IN PALÆOBOTAN Y 115 
stone) having beds of grit and gravel and often showing oblique lamina- 
tion. Scattered trunks of trees are imbedded in the sand, sometimes a 
number together, with the ends ground or rounded off. Certain layers 
show interlaced stems of Sigillariæ and Calamites, and there are beds 
of coarse black shale with remains of finer plants toward the top. No 
trace of marine fossils have been found in this member, and it is thought 
to be the delta-deposit of a considerable river, laid down where the 
current was too strong for the deposit of muddy sediment. The alter- 
native view is that it was a sea-shore deposit at the mouth of such a 
river. The tree-trunks in this sandstone are in the same condition of 
decay and abrasion as the drift wood of a modern river, and are imbedded 
in the same way, a few trunks passing through the layers diagonally, 
but most lying parallel to the strata. 
The middle member of the group, or the Lower Cordaite shale, is 
that which contains the plant remains, insect wings, etc., which have 
been described by Sir William Dawson and others. They are in excel- 
lent preservation, except that they have been graphitized and their 
finer tissues obscured by slight regional metamorphism. 
In the alternation of mud beds, sandy shales and fine sandstones, 
this member simulates true coal measures and has more than once been 
mistaken for such. With its numerous beds of fine plant remains, its 
branching roots in situ, and the perfect condition of the buried plants, 
it is just such a deposit as would accumulate in the marshes and lagoons 
of a delta, subject to incursions of sand and silt of a river. 
The upper member of the group or Upper Cordaite shale consists 
of beds of coarser texture, though presenting similar alternations of fine 
and coarse material. In this member the plant remains are frequently 
much mascerated, and the whole member is composed of more calcare- 
ous beds than those below. Marine organisms begin to show in this 
division, but those found were in poor preservation. During the time 
when this member was deposited, the sea was encroaching upon the land 
and substituting coarser material for the fine mud of the lagoons and 
marshes of the previous time. 
Such is the physical aspect of this terrane, and such the probable 
conditions accompanying its formation ; one may now look at the 
objections to ranking it with the Carboniferous System. 
In appealing to a standard for the Carboniferous System in this 
region, we are accustomed to refer to the Joggins section in Nova Scotia, 
so ably described by Sir Charles Lyell, Sir William Logan and Sir 
William Dawson, as that which most clearly shows the several members 
of the Carboniferous System. The synopsis of this section published 
Sec. IV., 1901. 8. 
