Cohasset is founded upon a rock, and the making of that rock is so honestly and minutely recorded by nature that even those who take alarm at the word "geology" may read this record with ease. These rocky ledges that stare so proudly across the sea underlie, also, every inch of soil, and are of the same kind everywhere--granite. Granite is a rock which is formed under immense pressure and in the presence of confined moisture, needing a weight of fifteen thousand pounds upon every inch. Therefore, wherever granite is found we know that it has not been formed by deposit, like limestone and sandstone and slate and other sedimentary rocks, but at a prodigious depth under the solid ground, and by slow crystallizing of molten substances. There must have been from two to five miles of other rock lying upon the stuff that crystallized into granite. A wrinkling in the skin of the earth exposed the granite, a wrinkling so gradual that doubtless if generations of men had lived on top of the wrinkle they would have sworn it did not move. But move it did, and the superimposed rock must have been worn off at a rate of less than a hundredth part of an inch every year in order to lose two or three miles of it in twenty-five million years. As the granite was wrinkled up by the movement of the earth's crust, certain cracks opened and filled with lava, forming dikes. The geologist to-day can glance at these dikes and tell the period of their formation as casually as a jockey looking at a horse's mouth can tell his age. He could also tell of the "faulting," or slipping down, of adjacent masses of solid rock, which has occurred often enough to carve the characteristic Cohasset coast. The making of the rock bottom is a story which extends over millions of years: the making of the soil extends over thousands. The gigantic glacier which once formed all over the northern part of North America, and which remained upon it most of the time until about seven thousand years ago, ground up the rock like a huge mill and heaped its grist into hills and plains and meadows. The marks of it are as easy to see as finger prints in putty. There are scratches on the underlying rock in every part of the town, pointing in the southerly direction in which the glacier moved. The gravel and clay belts of the town have all been stretched out in the same direction as the scratches, and many are the boulders which were combed out of the moving glacier by the peaks of the ledges, and are now poised, like the famous Tipping Rock, just where the glacier left them when it melted. Few towns in America possess greater geological interest or a wider variety of glacial phenomena than Cohasset--all of which may be studied more fully with the aid of E. Victor Bigelow's "Narrative History of the Town of Cohasset, Massachusetts," and William O. Crosby's "Geology of the Boston Basin."