In places where the low ground is marshy, roads and railways often follow the ridge-lines of hills, or, as in Finland, the old glacial eskers, which run parallel to the shore.
Noteworthy local features in the landscape of the central lowlands are the eskers or gravel-ridges ((tsar), traversing the land in a direction from N.N.W.
Boulder-clays and sands, and gravels rearranged by water, occur throughout the lowlands; while the eskers or " green hills," characteristic grasscovered ridges of gravel, rise from the great plain, or run athwart valleys and over hill-sides, marking the courses of sub-glacial streams. When the superficial deposits are removed, the underlying rocks are found to be scored and smoothed by ice-action, and whole mountain-sides in the south and west have been similarly moulded during the Glacial epoch.
Glacial furrows, striae and elongated troughs are met with everywhere, running mostly from north-west to south-east, as well as asar or eskers, which have the same direction.
All along Cape Cod; eskers, kames and river terraces afford the plainest evidences of the extent of the glacial sheet.