Quaternary International 99-100 (2003) 59–71 A methodology to reconstruct small and short-lived ice-dammed lakes in the Appalachians of Southern Qu ! ebec Armand LaRocque a, *, Jean-Marie M. Dubois b , Brigitte Leblon a a Faculty of Forestry and Environmental Management, University of New Brunswick, Fredericton (New Brunswick), Canada b D! epartement de g ! eographie et t ! el ! ed ! etection, Universit ! e de Sherbrooke, Sherbrooke (Qu ! ebec), Canada Abstract Previous studies on the deglaciation of the Appalachians of southern Qu! ebec reconstructed only the most extensive ice-dammed lakes and the most stable glaciolacustrine water levels. They only used the best developed shoreline features, and thus were not able to reconstruct small or short-lived ice-dammed lakes, both being characterized by a weak development of their features. We propose a methodology to reconstruct glacial lakes which follows three main steps: (1) the mapping of shoreline features, generally the best developed ones, as in previous studies; (2) the delineation of the former shoreline for each water level, by also considering the less well-developed shoreline features which were found during field surveys designed as a function of the presumed shoreline position; and (3) the mapping of the maximum extension of the water plane, which includes the location of the former ice dam and of the former glacial lake spillway. In southern Qu! ebec, small ice-dammed lakes were numerous and important because they shaped the geomorphology of the region during the deglaciation. They are thus among the key components of a deglaciation model for this area. r 2002 Elsevier Science Ltd and INQUA. All rights reserved. 1. Introduction During the last deglaciation, many lakes existed along the southern margin of the Laurentide Ice Sheet in North America. Most of them were dammed by an ice margin retreating northwards blocking the normal drainage and ponding meltwater between the ice and water divides. In central North America, these condi- tions were especially favourable for the development of extensive glacial lakes, such as glacial Lake Agassiz (Teller and Clayton, 1983; Teller, 1987), glacial Lake Barlow-Ojibway (Veillette, 1988, 1994) and several other lakes in the Great Lakes region (Karrow and Calkin, 1985; Teller, 1987). Such favourable conditions also existed in the Appalachians of eastern North America, where less extensive lakes were mapped: among them are glacial Lake Hitchcock (Lougee, 1939; Jahns and Willard, 1942; Larsen and Hartshorn, 1982; Larsen and Koteff, 1988) glacial Lake Vermont (Chapman, 1937; Stewart and MacClintock, 1969; Clark and Karrow, 1984) and glacial Lake Candona (Parent and Occhietti, 1988, 1999). In the Appalachians of southern Qu ! ebec (Fig. 1), the existence of former ice-dammed lakes was known since the beginning of the last century by the identification of shoreline features (Hitchcock, 1895, 1908) and of varves (Antevs, 1925, 1928), but the first lake reconstructions began only after the 1960s. The two largest ice-dammed lakes of the region were studied: (1) the Sherbrooke Phase of glacial Lake Memphremagog (McDonald, 1968; Stewart and MacClintock, 1969; Gadd et al., 1972; Boissonnault et al., 1981; Boissonnault and Gwyn, 1983; Parent and Occhietti, 1988); and (2) the 425–460 m water level of glacial Lake Papawitekw (LaRocque, 1999), a large water body dammed in the upper part of the Chaudi " ere River valley (Shilts, 1981; A. Larocque et al., 1983). Other water levels were also recognized in the Coaticook and Moe River valleys (Thornes, 1964, 1965; Morissette and Dubois, 1991; Dubois and Morissette, 1994) and in the Saumon River basin (A. Larocque et al., 1983; G. Larocque et al., 1983). However, no other ice-dammed lake has been recon- structed in many valleys of the area, although some glaciolacustrine features were found. Gadd (1983, 1984a,b) therefore concluded they were absent, but this last hypothesis was not in accordance with the literature considering the presence of shoreline features and of *Corresponding author. Fax: +1-506-453-3538. E-mail address: bleblon@unb.ca (A. LaRocque). 1040-6182/02/$-see front matter r 2002 Elsevier Science Ltd and INQUA. All rights reserved. PII:S1040-6182(02)00112-X