Correspondence—W. S. Gresley. 579 
a series of domes, but ‘stoped’ out portions of the sides and lower 
surface of the arches, the fragments torn off from walls and roof by 
the invading granite being found scattered throughout the mass of the 
invading rock; this ‘stoping,’ however, probably developed only 
a small part of the space which the granite now occupies; (5) the 
invading granite not only exerted a mechanical action upon the 
invaded strata, but also gave rise to a variety of metamorphic products, 
among others amphibolite produced by its action in the limestone, 
which accounts for the fact that while the invaded strata are chiefly 
limestone, the fragments of the latter, where found in the granite, 
consist of amphibolite; (6) the mvading bathyliths and allied 
intrusions of granite occupy the greater part of the great Northern 
Protaxis of Canada, which has an area of approximately 2,000,000 
square miles. It has, therefore, been considered advisable to restrict 
the name Laurentian to this great development of the ‘ Fundamental 
Gneiss,’ which, although intrusive into the Grenville Series, never- 
theless underlies and supports it; (7) the relation of the Grenville 
Series, which forms the base of the sedimentary portion of the 
geological column in Kastern Canada, to the Huronian and Keewatin 
Series, which are the oldest stratified rocks in the western part of the 
Protaxis, has yet to be determined, the two not having so far been 
found in contact; nowhere, moreover, either east or west, has the 
original basement on which the first sediments were laid down been 
discovered; these are everywhere torn to pieces by the granite 
intrusions of the Laurentian. 
At 8 p.m. on Wednesday, November 13th, the actual anniversary 
of the foundation of the Society in 1807, the Fellows met informally, 
to the number of about 100, at the Society’s Rooms in Burlington 
House, where the various addresses presented on September 26th 
were on view. 
“The History of the Geological Society of London,” by Horace B. 
Woodward, F.R.S., illustrated with twenty-eight portraits and 
reproductions of medals, is now obtainable at the Society’s Apartments, 
price 7s. 6d. nett; and at the reduced price of 6s. by Fellows only. 
CORRESPONDENCE. 
RE CONE-IN-CONE. 
Srr,—Touching the origin and age of this formation or structure, 
would such of your readers as have made observations in this 
connection kindly tell us at what depths below the present surface 
they have discovered or noted this rock-structure ? We know that the 
Coal-measures contain it, but at what depth in pits (shafts, boreholes, 
or underground workings) has it been found? Reports state that it 
occurs in the Cambrian, Lower Silurian, Devonian, as well as in com- 
paratively recent epochs, but the point is: is it as o/d as the strata 
enclosing it? (See vol. 188, 1894, etc.) W. S. Grestey. 
Durrietp, DrErsBy. 
13th Nov., 1907. 
