1895.] Geologu and Paleontology. 663 
far, the explorations made at a distance from the porphyrite have been 
barren of commercial results; but from the occurrence of the one in 
chutes, which, although constituting a part of the ‘blanket,’ vary in 
width (being generally narrow close to the surface and widening in 
depth), it is possible that large bodies, somewhat of the nature of the 
Incline or the Bella Chute, may exist stillin the unexplored portions 
of the property. 
“ The occurrence of new bonanzas, such as the Bridal Chamber and 
the Bunkhouse, is scarcely to be expected, as the conditions under 
which they appear to have been found, that is, the triple contact of the 
Blue and Crinoidal limestones and the porphyrite, are not known to 
exist at any points as yet unexplored, and the overflow of porphyrite, 
has been so thoroughly prospected as to leave but little unexplored 
ground of that class. 
The most promising quarter for further exploitation would seem to 
be the extension of the Grande chute cut at some point south of the 
John’s shaft workings, where, as before mentioned, large chutes of 
iron-flint, too low in silver for profitable working, were cut. Other 
points which should be prospected are the extension of the Bella Chute 
beyond the point where it has been cut off by the Columbia fault.” 
(Trans. Am. Inst. Mining Engineers). 
Erosion of Submerged Limestones.—The limestones in the 
bottom of a certain portion of Lake Huron are undergoing a peculiar 
kind of erosion, which, from want of better terms to describe the 
process, which may be called honeycombing and pitting. Mr. Robert 
Bell has made a study of this phenomenon and after considering the 
physical characteristics of the eroded rocks, their age and the possible 
origins of the erosions, the author arrives at the following conclusions, 
The erosion is due to: 
I. The internal structure of the limestone itself. 
II. A small quantity of acid in the water acting for a great length 
of time. 
III. A considerable depth of water, the hydrostatic pressure seem- 
ing to promote the dissolving of the rock. 
IV. Freedom from sediment during the long time required. 
V. The rock must be exposed to the open or free action of the 
water. 
VI. Shifting currents in the water appear to assist the process, 
(Bull. Geol. Soc. Am., Vol. 6, 1895). 
45 
