At Shelburne Falls the present elevation of these features is 300 feet, at St. Albans 440 feet, and at Roxton, Quebec, 552 feet. It will be noted that proceeding from south (Shelburne Falls) to north (Roxton) a difference of over 250 feet is found between features formed at an identical time in the past. The water in any lake is practically level. It therefore follows that the present 300, 440 and 552 foot elevations of the shoreline features are the result of subsequent tilting of the earth’s surface. Perhaps the following reference to the water level of present Lake Champlain will help in your understanding of this tilting. The present-day average level of the water in Lake Champlain is about 92 feet above the level of the Atlantic Ocean. This water-level elevation is constant throughout the extent of Lake Champlain and _is not_, say, 92 feet at Button Bay and 192 feet at Burlington. Again, the only way that features demonstrating past lake margins or levels could, for any one lake or lake-stage, now exist at different elevations would be if some earth movements took place after the formation of the features, resulting in a change from their original elevations. The earth’s crust has been tilted, higher in the north than in the south, during recent times. This tilting provides the clue to the formation of present-day Lake Champlain. Major tilting took place after the maximum marine invasion. Tilting continued, at a decreasing rate, perhaps, to the present day. This tilting, with greater relative rise in the northwest, eventually reached a point where marine waters were excluded from the Champlain Basin. Fresh water slowly diluted the salty marine water. The lake gathered more and more fresh water through rain and melting snow, and a new outlet formed in the north, in the approximate location of the present Richelieu River. The area of Lake Champlain slowly increased to its present size, and the clays which once formed lake and sea bottom became the “hard earth” of the Champlain Lowlands. Continued tilting caused flooding of the streams, especially in the southern portion of Lake Champlain, such as the now swampy Otter Creek and its tributary Dead Creek (see map, Fig. 2). This concludes the story of the Park clays. From the rocks which crop out within a short walking distance of Button Bay State Park a much older segment of geologic history can be studied. THE OLDER ROCKS