Why the name Button Bay? H. M. Seely (1910, p. 274)[3] when discussing the shoreline of this bay states, “Besides shells, _concretions_[4], some of strange imitative forms (many shaped like animals), are loosened from the clay.” He goes on to say that a “form particularly abundant in the banks of the bay (and on the beach) has the shape and size of a turned wood button-mold (mold is commonly spelled ‘mould’ by the British), a disc with a hole in the center, plane (flat) on one side and convex on the other” (see Fig. 3 and cover picture). The abundance of these button mold-shaped concretions obviously led to the older name, Button Mould Bay which was later shortened to Button Bay. THE GEOLOGY OF BUTTON BAY STATE PARK If the visitor confines his wanderings to the State Park the most conspicuous geological features, or clues to the Park’s past history, are concentrated in the clay banks and adjacent beach which border Lake Champlain (see Fig. 4). The clays which cover the entire Park record thousands of years of rather recent events, _geologically speaking_[5], which took place in the Champlain Valley. These clays also record a very significant phase in the development of present Lake Champlain. Before discussing the clays it will be necessary to outline some of the geological events which preceded the deposition of the clays, that is, some of those events which took place as the last glacial ice lobe slowly retreated up the Champlain Valley and into Canada. The author has borrowed heavily from an article by Donald H. Chapman entitled “Late-Glacial and Post-glacial History of the Champlain Valley” which was published in the 1941-1942 “Report of the State Geologist on the Mineral Industries and Geology of Vermont, twenty-third of (the) Series.” [Illustration: Figure 3. Water-worn concretions seen on the beach of Button Bay State Park. The button-mold shape of some concretions led to the incorporation of the word “Button” in the name Button Bay (Originally, Button-Mould Bay). The chisel portion of the Alpine ice ax head is about 5 inches long.] During the final retreat of the last ice sheet to invade the New England states (some 11,000 to 12,000 years ago) an ice lobe, which occupied the Hudson-Champlain Valley, slowly wasted northward toward the Canadian border. Melt-water derived from the melting glacial ice together with atmospheric water (rain and snow) formed a succession of lakes dammed on the north by the glacial ice. These lakes emptied to the south through the Hudson Valley. This succession of lakes and intermediate lake stages will be discussed in the following paragraphs. [Illustration: Figure 4. View of beach, Button Bay State Park, looking toward the southeast. The beach demonstrates several water-level and storm-level debris lines. Note the conspicuous lack of sand on this “clay” beach.]