The study of the great mountain ranges of America by Rogers, Hall, Dana, Le Conte, Hunt, and other geologists, has now thrown much new light on the earth-movements which precede and accompany the formation of mountain chains. As the result of these researches, it appears certain that the preliminary stage in the formation of every mountain system has consisted in a long-continued depression of the area which is afterwards to become its site; and, in consequence of this prolonged subsidence, the accumulation of an enormous thickness of stratified rocks, within the great trough so formed, has taken place. Of this character, as is now well known, have been the earlier manifestations of the subterranean forces that were concerned in the formation of the Appalachians, Green Mountains, and other American ranges; the districts in which they are situated were subjected to long-continued depression, which permitted of an abnormal development of all the members of the sedimentary deposits formed during this initiatory period; and it was by the folding, metamorphism and crushing together of this abnormally thickened portion of the earth's crust that the indurated and elevated masses have been formed which denudation has sculptured into the existing mountain chains.

Aspect of Newfoundland.—It has been suggested that the so-called glacial effects which are universally seen in temperate, and even in tropical regions, may in many cases have been due to an ocean on which great icebergs floated. These, as they moved from point to point (like huge pepper-castors), strewed broadcast boulders and detrital matter, such as are now to be seen over an area like that of Russia and parts of North America. The effect of the force of impact of these tremendous masses has also been dwelt on, and the way in which they could grind, smooth down, or rub up the surface of a submerged area, has also often been referred to.

Polypary four or five inches in length, straight or very slightly curved, attaining a maximum diameter of one-twelfth of an inch. Hydrothecæ short and broad cups, with subquadrangular section, 20 to 24 to the inch, without overlap, inclined at an angle of about 45°; outer edge convex distally, proximally impressed; apertural margin deep, concave, at right angles to the general direction of the theca; denticle triangular and inornate.

As a contribution to our knowledge of the formation of these very interesting “natural embankments of the sea,” I may point to a little bay in Anglesea, immediately westward of the Bryn Ddu Limestone quarries on the north-east coast of Anglesea, about two miles and a half westward of Puffin Island. This little bay is not more than about a furlong across, and may be roughly described as semicircular in form, lying nearly due west to east from point to point. From being in miniature as it were, the ridge can be readily studied, and it is very striking to see how, commencing in the westward as a beach, it gradually rises into a ridge having very steep sides. No less remarkable is the way in which the stones increase in size as the ridge does in height. At the west end it may be described as composed of Limestone pebbles, with here and there a boulder, while at the east end it is built up almost entirely of large limestone boulders and blocks, many containing from one to two cubic feet and some more. Intermixed there are boulders from the size of the closed hand and upwards. The larger blocks are sub-angular and rounded, and no doubt get gradually worn down smaller and rounder, until they become “boulders.” by being moved about, by the sea; but some on the other hand, being thrown over on to the back of the bank, cannot be further affected by the waves. In this ridge, as I have pointed out is the case with the Chesil Bank, the stones follow the law of the bank itself, the largest being collected to form the highest part of the bank, which in both occurs where the wave-action is most intense.

I Fear I must express my ideas very indistinctly, seeing that I am so frequently misunderstood by my critics. Quite recently a well-known American astronomer, in reviewing my book, “Climate and Time,” devotes nearly a dozen pages to the refuting of views most of which I have never held. And in the July Number of the Geological Magazine I am sorry to find a repetition of the same thing.