Correspondence—Mr. H. B. Woodward. 143 
comparatively rare. Now, as we have to deal with rocks having 
three well-marked varieties of texture, we ought to have a correspond- 
ing number of terms for their designation; and I do not see why 
rocks which exhibit such varieties should not be described as slates, 
schists, and foliated schists. 
However this may be, the term schist certainly ought not to imply 
or include foliation (or arrangement of two or more minerals in 
separate layers), as there is no necessary connexion between the 
two ideas. No doubt a foliated rock will nearly always be a schist, 
as it will split readily, but there are plenty of schistose rocks which 
are not foliated. 
Now the texture of the Brazil Wood rock is precisely of this 
character, and as two micas are its chief constituents, I ventured to 
eall it a micaceous schist; but not mica-schist, and only pro- 
visionally, for, as stated in my paper, I regard it as one of a group 
of rocks which have not yet received distinctive names; they are 
rocks of great interest, and I hope to have something more to say 
about them on a future occasion. It appears to me, therefore, that a 
new name which is fairly descriptive of the rock must be preferable 
to an old one which is altogether inappropriate. S. ALLPORT. 
Birmincuam, January 12th, 1880. 
MR. H. B. WOODWARD’S ADDRESS TO THE NORWICH GEOL. SOC. 
Srr,—The legend to the woodcut given on p. 75 of the February 
Number of the Grou. Mac. having been accidentally omitted, the 
following explanatory statement is necessary :— 
The lowest bed touched in the Subwealden Boring is the Oxford 
Clay, the succeeding beds (above the dotted line) traced northwards 
are Corallian, Kimmeridge Clay, Portland Beds, Purbeck Beds, 
Hastings Beds, Weald Clay, Lower Greensand, Gault and Upper 
Greensand (together), Chalk. The last two divisions continue as far 
as the boring at Wells. The uppermost beds at London and 
Harwich are the Eocene; those at Diss and further north are chiefly 
glacial deposits. The lowest bed passed through in the boring at 
Wells is the Lower Greensand, beneath which the Kimmeridge Clay (?) 
is just reached. Below the dotted line (on the section) three divisions 
of Paleozoic rocks are shown-—the uppermost, distinguished by thick 
black lines, represents the Carboniferous rocks; the middle ‘“ dotted” 
division represents Devonian rocks and Old Red Sandstone ; and the 
lower “jointed” division represents the Silurian rocks. 
The Vertical Scale was 2000 feet to one inch. 
H. B. Woopwarp. 
ECCENTRICITY AND GLACIAL EPOCHS. 
Srr,—In Mr. Hill’s paper on “ Hecentricity and Glacial Epochs,” 
the following paragraph occurs in reference to Dr. Croll’s contention 
that the accumulation of masses of snow and ice during the winter 
would tend to lower the summer temperature: “The First alleged 
reason,” Mr. Hill says, “is the cold produced by masses of ice 
