"The rains and the rivers, with the help of some other things, have made all the lakes in the world. One of these helpers is a bright-eyed creature with two legs; another a little creature with four legs and a third a great big thing with no legs at all!" (I said it like this: "G-R-E-A-T B-I-G T-H-I-N-G," and opened my eyes wide for the benefit of the younger members of our "pebble parties," as these little gatherings came to be called.) The great big things, as you have already guessed, were the glaciers of the Ice Age. We have had specimens of their work in the story of how the Great Lakes were made. The four-legged lake makers are the beavers. They live on the margins of quiet, shallow ponds--really little lakes--which they make for themselves by gnawing down trees and building dams. And the bright-eyed creature with two legs--can't you guess who he is? If you never helped make little lakes of your own by damming up a brook or a roadside rivulet, you have missed a lot of fun. WIDE RANGE OF SIZE IN LAKE FAMILY But you _must_ have made them; what boy hasn't? And those little ponds or puddles were lakes, while they lasted, just as much as the great Lake Superior is a lake. Even lakes that are called lakes and get their names (and often their pictures) in summer resort folders, differ in size, ranging from little affairs that are not much larger than the pond in the meadow, to Lake Superior, with its 31,000 square miles; and in depth, from a few feet to 5,618 feet in the deepest part of Lake Baikal. You see if you touched bottom there you would have to keep going for over a mile. "And there's all the way back!" said the High School Boy. [Illustration: THE GREAT LAKES OF TO-DAY AND THE GREATER LAKE OF YESTERDAY The farmers of Canada and the Dakotas now sow their harvests and reap their golden grain on the bottom of the great inland sea of the Ice Age, Lake Agassiz. It was larger than all the Great Lakes of to-day put together. It is known how big this lake was from its old beaches, which can easily be made out all around the margin shown on the map. ] [Illustration: THE BLUE LAKE IN THE VOLCANO'S MOUTH In the mouth of a dead volcano lies one of the most beautiful lakes in all the world, the chief attraction of Crater Lake National Park. This model of its basin tells how nature did the work. The steep sides and the glacial valleys show that the top fell in when the lava that helped build the volcano sank back and so left it without support. If the top had blown off, as volcano tops sometimes do, the valleys would have been filled with débris. Later there was another outbreak, but so small that it only built that little volcano in the big volcano's mouth. Notice the tiny crater? This baby volcano rises above the waters of its mimic ocean and makes an island, just as so many volcanoes of the great Pacific make the far-flung islands of the Southern Seas. ]