DESCRIPtlON OF THE DEPOSITS SIS 



subaerial erosion. This shows especially well in plate 14, figures 1 and 2. 

 It has been suggested that the gravels were formed beneath sealevel and 

 the clay deposited directly on tlie uneven surface as soon as the inclosing 

 ice melted. Katz and Keith have recently strongly advocated such a re- 

 lation between the moraine and "Leda'' clay along the coast of Maine.* 

 Such does not seem to have been the case in the region about Waterville 

 for the following reasons : 



1. If the esker were submarine, it does not seem probable that a basal 

 conglomerate, sucli as is so clearly shown in plate 13, figure 2, locality 5, 

 would have formed. As Katz and Keith pointed out,'^ the uniform char- 

 acter of the clay requires fairly deep water as the condition of origin. 

 It does not seem likely that such a deep water condition of origin, sup- 

 posed to have been realized at once on the melting of the ice, would favor 

 the formation of a basal conglomerate far up an estuary protected by 

 many rocky islands. On the other hand, a gradual encroachment of the 

 sea on gravel and sand should form just such a deposit. 



2. If the wave action had been strong ejiough to form such a basal 

 conglomerate under conditions of submarine origin of the esker, it seems 

 that the static conditions would have allowed the development of a flatter 

 contact. Such a sloping, irregular contact, however, would be the natural 

 result of a fairly rapid submergence. 



3. If the irregular contact of gravel and marine deposits is the product 

 of violent torrents near the mouth of an esker stream in a submerged ice- 

 tongue, there should be some ' evidence of the cross-bedded gravels and 

 sands of scour and fill, instead of the clean-cut contacts illustrated; also 

 the erosion channels formed under those conditions would seem less likely 

 to be at right angles to the axis of the esker. 



4. Fossils occur even in the basal conglomerate of plate 13, figure 2. 

 If this had been formed by wave action immediately on the disappearance 

 of the ice, would life have been present at once, even in a fauna of Arctic 

 affinities? Especially convincing is the occurrence, just a few feet above 

 the base of the clay, at locality 3, of four species of plants, represented by 

 fairly well preserved leaves. These are typical of climatic conditions 

 much the same as exist today in this region, and it hardly seems likely 

 that such conditions could have been restored so soon after the ice had 

 melted from an area as large as that covered by the marine clays of this 

 part of Maine. 



5. A lowering of the sealevel on the withdrawal of the water locked up 

 in the ice-sheet and a re-advance of the sea as this water was gradually 



* Professional Paper 108, U. S. Geol. Survey, pp. 26, 27, and summary. 

 » Op. clt, p. 24, evidence 4. » 



