. Elements of geology : a text-book for colleges and for the general reader. Geology. 136 IGXEOUS AGENCIES. which increases as we go north until it attains a maximum of five to six feet per century. These observations were made under the direc- tion of the Swedish Government by means of permanent marks made at the sea-level, and examined from year to year. That similar changes have been in progress for thousands of years, and have greatly increased both the height and the extent of these countries, is proved by the fact that old sea-beaches, full of shells of species now living in the neighbor
. Elements of geology : a text-book for colleges and for the general reader. Geology. 136 IGXEOUS AGENCIES. which increases as we go north until it attains a maximum of five to six feet per century. These observations were made under the direc- tion of the Swedish Government by means of permanent marks made at the sea-level, and examined from year to year. That similar changes have been in progress for thousands of years, and have greatly increased both the height and the extent of these countries, is proved by the fact that old sea-beaches, full of shells of species now living in the neighboring seas, are found fifty to seventy miles inland, and 100, 200, and even 600 feet above the present sea-level. In some places, the country rock, when uncovered by removing superficial deposit of beach- shells, is found studded with barnacles like those which mark the present shore-line (Jukes). The rising area is about 1,000 miles long north and south, and of unknown breadth It may embrace a considerable portion of Russia. Lyell estimates the average rate as not more than two and a half feet per century. At this rate, to rise 600 feet would require 24,000 years.* Similar raised beaches are found in nearly all countries. We give these as examples of an almost universal phenomenon, which will be again more perfectly described in the chapter on the Quaternary. Greenland.—For obvious reasons, evidences of elevation are much more conspicuous than evidences of depression. One of the best-ob- served instances of the latter is that of the coast of Greenland. This coast is now sinking along a space of 600 miles. Ancient buildings on low rock-islands have been gradually submerged, and experience has taught the native Greenlander never to build his hut near the water's edge. the deltas of the Mississippi, the large rivers, there are unmistakable evidences of gradual depres- sion. These evidences are fresh-water shells, and planes ;eelEEF~j^[J^ of vegetation, or dirt-beds, far below the
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectgeology, bookyear1892
