UPPER CRETACEOUS. 



683 



In 1890 Shaler was able to reexamine the section at Gay" Head, then more clearly 

 exposed by exqeptional rains, and determined that the strata were closely folded, 

 not monoclinal. He distinguished certain divisions of the "Vineyard series" as 

 foUows:^^"^ 



The section at Gay Head is apparently divisible into two tolerably distinct elements, viz, 

 a lower division, the upper limits of which are not determined, which is likely to prove of Creta- 

 ceous age; and an upper part of the section, which from the fact that it contains bones of ceta- 

 ceans is likely to prove of Tertiary age — the two together forming the greater part of the longi- 

 tudinal section of Gay Head. Above these two more ancient portions of the escarpment lies 

 an extended series of unfossilif erous sands, which apparently belong to a somewhat later age than 

 the other portion of the section. To this age we may also presumably assign the extensive 

 series of beds exhibited in the Weyquosque series. These later-formed beds are, at least in the 

 Weyquosque chflFs, deposited unconformably upon the earlier series. A portion of these later 

 unfossUiferous sands are involved in the contortions at Gay Head, and a portion of them lie 

 unconformably upon the edges of the beds which were involved in the dislocation. It seems 

 Ukely, therefore, that this later series will in the end be found divisible into two parts — a por- 

 tion which was laid down before and a portion formed after the greater part of the disturbance 

 had been effected. 



Shaler was in doubt as to the age of the different divisions. White ^^* identified 

 a number of Cretaceous plants from " several localities and horizons in the Vineyard 

 'series.'" Dall^"" described Miocene faunas apparently from the same closely 

 folded strata, and Pliocene forms from sands which lie unconformably upon them. 

 (See Chapter XVII, p. 823.) 



Supposed Cretaceous clays have been reported in well borings in Boston. W. 0. 

 Crosby ^^^ was the first to suggest that these clays were pre-Pleistocene. Later 

 F. G. Clapp "*' reported these distinctive clays from several wells in Boston, and 

 discussed in detail the boring at Ames Building, the samples of which he examined 

 critically. The following log and notes are taken from Clapp's paper: 



Record of boring at Ames Building, Boston. 



Coarse sand and gravel 



Sand 



<3ravel and band 



Coarse gravel and white clay 



Stony sand, gravel and clay with much water (very hard) 



Blue clay 



Fine sand 



Clay, sand, and gravel, with water (till) 



Hard dry nearly white clay, with bowlders 



Slate (Carboniferous) 



The material below 77 feet is dry and in a previous boring had been called rock and not 

 entered by the drill. All the samples of this bed were seen by the writer and found to consist 

 mostly of a very fine grained gray to white clay, which became plastic when wet. It varied 

 from very soft and putty-like to nearly as hard as the underlying slate. The material when 

 examined by Dr. W. T. Schaller, of the United States Geological Survey, was found to consist 

 of Si02 = 59.18 per cent and (AljOg, Fefi^, PA? Ti02) = 27.11 per cent, thus being a very 

 pure clay. * * * 



