DESCIUPTIOK OF TJTE DEPOSITS 317 



mind there is no field evidence of a second ice-advance in the vicinity of 

 Waterville which is not open to one of these alternative interpretations.* 



THE YOUNGER SANDS AND CLAYS 



The younger clays and sands consist of bine cla^'S overlain by coarse, 

 loose, stratified sands, which at times become gravelly toward the base. 

 The clay is massive and exceedingly tough. The sands are fairly well 

 rounded, probably nioie so than any others of the area. These deposits 

 express themselves toi)Ographically in the form of a terrace, only slightly 

 dissected, whose elevation is about 115 feet above sealevel. The larger 

 part of Waterville is situated on this terrace. Fo fossils have been found 

 in this clay. On tlie clay surface, at the contact of clay and sand as 

 exposed in cellar foundations, I have found very ])crfectly developed mud- 

 cracks. An example of these is shown in plate Iv, figure 2. The terrace 

 is sometimes sharply, sometimes indistinctly, bounded by a scarp. The 

 best development of the scaq:> is seen about 100 yards west of the station. 

 where it is fairly abrupt and 40 feet high. The face of this scarp is 

 gravel, covered by fossiliferous marine clay, ^ot far to the north of hci'o 

 the scarp is ledge, iu turn overlain by a similar fossiliferous clay. That 

 the clay of the terrace is yoiingei- tlian the gravel was shown concliisiNcly 

 this past summer when the city raji a sewer line near the base of the 

 scarp, digging through clay: at the same time they were digging gravel 

 from a ])it in the scar]), penetrating several feet lower than the neai'-by 

 clay. The Kennebec Eiyer has cut through these clays into the under- 

 lying slate and is still actively downcutting. 



On the Colby College campus ledge outcrops on the river back of the 

 college at an altitude of 90 feet. A contour map of the campus made the 

 past summer with 5-foot contour intervals shows its highest elevation to 

 be 117 feet. The combined thickness of clay and sand here would prob- 

 ably not be over 25 feet. Excavations for new dormitories penetrated 

 the clay, but did not pass through it. On the other hand, an old well 

 about one-half mile away penetrated over 70 feet of sand and clay. Ac- 

 cording to my conception, however, this thickness may represent mostly 

 marine clay out of which the terrace was cut, as pointed out in the next 

 paragraph. However-. I have never seen anything which seemed to repre- 

 sent a contact of marine clay with the overlying clay of the terrace. 



Elevation of the land followed the deposition of the marine clay, grad- 

 ually bringing it above sealevel. The stream resulting from the with- 



^ Locality 6 may offer a possible exception to this statement. Here older gravels, 

 clay, and younger gravels come to the surface in a rounded, very drumlin-like form 

 (plate 17, figure 1). 



