In the Adirondack Mountains, for example, most of the lakes, like the well-known Lake Placid, Saranac Lakes, Long Lake, and Schroon Lake, have their waters ponded by single dams of glacial débris across valleys. In some cases a series of such dams blockades a valley and forms a chain of lakes like the well-known Fulton Chain in the Adirondacks. Less commonly the lake may have its waters ponded by two natural dams of glacial débris, one across a valley at each end of a lake. A very fine, large scale example of the last-named type is the famous Lake George in the southeastern Adirondacks. It is over 30 miles long and from 1 to 2-1/2 miles wide. It lies in the bottom of a deep, narrow mountain valley, mountain sides rising very steeply from a few hundred feet to 2,000 or more feet above its shores. There are many islands, especially in the so-called "Narrows," thus greatly enhancing the scenic effect. The valley itself has been produced by a combination of faulting and erosion. There was a preglacial stream divide at the present location of the "Narrows." This divide was somewhat reduced by ice erosion when the deep, narrow body of ice plowed its way through the valley during the Ice Age. During the retreat of the ice heavy morainic accumulations were left as dams across the valley at each end of the lake. Another remarkable body of water, similar to Lake George in its origin, is Chautauqua Lake of western New York, famous for its Chautauqua assemblies. It lies 1,338 feet above sea level, with its northern end near the edge of the steep front of the plateau overlooking Lake Erie. Chautauqua Lake really consists of parts of two valleys, one sloping north and the other sloping south, each dammed by glacial deposits. The famous Alpine lakes--Garda, Como, and Maggiore--have resulted from deposition of glacial morainic materials under conditions different from those above described. In these cases great mountain or valley glaciers once flowed down the valleys and spread out part way upon the Italian plain. Great accumulations of glacial débris took place around the borders of the glacier lobes, and, after retreat of the ice, the glacial deposits acted as dams ponding the waters far back into the mountain valleys.