Attention is called to an interesting article by Dr. Horace C. Hovey, in this week's Supplement, i announcing recent discoveries concerning the Isles of Shoals. This picturesque group is nine miles from i Portsmouth, and includes nine small islands, five of which belong to Maine and four to New Hampshire. : Although discovered in 1614 by Captain John Smith, : and visited by thousands of tourists, their geology has been neglected. After briefly giving a few historical facts, Dr. Hovey tells what he found during his ex- -plorations among the rumpled and twisted rocks of this group. There are proofs that Star, Haley, Cedar and Malaga islands are undergoing a process of elevation, havingrisen six feet within fifty years. Potholes that once were at tide level and used by the fishermen as basins for cleaning fish are now a hundred feet back from the sea, and six feet above the ordinary tides. The channel between these islands was formerly six feet deeper than it now is. The petrography of the islands has only been partly worked out; but the signs of igneous action are impressive. Dikes of diorite and gneiss and seams of quartz and feldspar run in every direction. The trap rock yields more readily to the action of the sea than do the granitic rocks, and on being worn away leaves channels through which the waves rush with violence. In some cases the work is not yet complete, and the huge basaltic blocks lie like gigantic stairs, thus justifying the etymology of trap from ' trappa," meaning steps. A remarkable column on Appledore Island is de scribed that is eleven feet in diameter, and that must once have been as much as twenty-five feet high, but now has been singularly sliced off by the waves. In shape it is sharply hexagonal. The rock is light colored granite crushed and baked, and protrudes from a mass of black gneiss,beyond which are walls of white granite. It is an altogether unique occurrence. i The violence of the waves that beat about these islands would seem incredible, were not so many proofs at hand. Some of them are given. The Laightons, who own most of the islands, built a wall to pro tect their Appledore hotel. The wall was six feet high and six feet thick. But a single winter storm broke it down and scattered the stones in every direction. Last winter a storm carried great bowlders completely across the islands. A bowlder weighing many tons was tossed by the waves and lodged on I the cliff of White Island fifty feet above the sea level. The lightning has also done its share in the work of demolition. Glacial action has been powerful. These causes combined, glacial, aqueous, igneous and electrical, have rent these islands apart, severed them from the mainland, and comminuted their rocks into the masses of sand now piled up as dunes about the mouth of the Merrimac.
This article was originally published with the title "The Isles of Shoals" in SA Supplements 40, 1035supp, 274 (November 1895)