Between Hadley and Easthampton, the river runs through a gorge in a greenstone ridge nearly one thousand feet high. The portion of the ridge east of the river is called Mount Holyoke, and the portion west of it Mount Tom. This gorge is very interesting because of showing the amount of erosion that can be performed by water in long periods of time. In all probability the bed of the Connecticut was, in remote time, much higher than it is at present, and the river itself much larger, and the rich, alluvial plains that border it at the present day were once beneath its broad waters. At one point in the gorge a mass of greenstone projects some rods into the river from the west side of Holyoke, having a perpendicular face twenty to one hundred feet high. This mass exhibits a columnar structure similar to that of the Giant's Causeway. The structure is not very evident above the level of the river, but at low water, by rowing along the face of this rock one can find the tops of regular columns reaching nearly to the water's surface. On the opposite side of Holyoke, not far from the road going to the summit, is another interesting example of these greenstone columns. Professor Hitchcock named these respectively Titan's Pier and Titan's Piazza; and any lover of geology is well repaid for the labor spent in getting a view of them. Holyoke, though two hundred feet lower than Tom, is more frequented by visitors. The ascent is not very difficult, and the view from the summit is both grand and beautiful. The river is of course the most attractive feature in the landscape. Far to the north and south it stretches, like a silver, sinuous thread, gradually becoming narrower until it is lost in the distance. Owing to an optical illusion the river seems to ascend in both directions, and at the points where it is lost to view, seems on a level with the eye. It is one of the best examples of this species of optical illusion to be found in this part of the country. A half century ago the river between this gorge and a point about a quarter of a mile north of it made a most magnificent curve, three miles long; but during the flood in the spring of 1840 a straight channel was cut across, and the water continuing to flow in the old bed as well as the new, there existed for some years what may be called an island in the river.