DETAILS OF THE GAY HEAD SECTION. 451 



island. A little to the southwest of the highest point in the section the 

 moraiual material probably has a thickness exceeding 100 feet. This sec- 

 tion is intended also to show that while the Cretaceous and Tertiary beds 

 (the age of which cannot at this point be determined) lie at a high angle, 

 the average declivity exceeding 45°, there lies against them to the north- 

 west a thick section of beds supposed to be of preglacial or interglacial 

 age which have not been disturbed. These horizontal beds are probably 

 of the same age as those which lie unconformably upon the upturned and 

 eroded strata at Gay Head, where they are shown both in the northern and 

 southern extremities of the section. As is indicated in the section, they are 

 well developed from 800 to 1,200 feet west of the steamboat landing. Simi- 

 lar deposits exist along the northwest face of the island from Chappaquon- 

 sett pond westward. They probably also occur at the base of the cliffs at 

 Cottage City, and also in the easternmost portion of the Nashaquitsa cliffs 

 near Chilmark pond. On the northern shore and also near Chilmark pond 

 these deposits contain occasional waterworn fragments of fossils derived 

 from the Tertiary strata against which they lie. 



The Gay Head section (fig. 2) begins near the steamboat wharf on the 

 shore to the northeast of the light, and extends in a general westerly trend 

 for about 1,000 feet ; next in a prevailingly southerly course for about 2,500 

 feet; then it swings in a southeasterly direction, where it terminates at 6,200 

 feet from the point of beginning. The delineation exhibits the apparent 

 dips at the points of outcrop, and therefore must not be regarded as a cross- 

 section. The object of the delineation is to give as nearly as possible the 

 aspect of the beds in the present condition of their exhibition. Owing to 

 the fact that the strata are evidently very discontinuous, it is not possible to 

 determine their attitudes at any distance from the outcrop. At certain 

 points, as, for instance, at 4,100 feet from the wharf, the beds are delineated 

 in as yet unexplained positions, care being taken to exclude from such de- 

 lineation strata which had come to their position by slipping down the face 

 of the cliff. At the point indicated as " the Devil's den " there is a deep 

 recess in the face of the cliff. Here the soft clays and sands, standing at a 

 high angle, have yielded readily to erosive agents which have carried the 

 escarpment back more readily than it has elsewhere been worn away by the 

 sea. 



A number of thin lignites, apparently having no considerable extension, 

 are omitted. All the other distinctly determined strata are drawn. The 

 blank spaces indicate portions of the escarpment at present so far covered 

 by detritus that the stratigraphy of the underlying beds has not been deter- 

 mined. At only one point has it appeared possible, in the present state of 

 our information, to infer from the existing remnants of the strata the posi- 

 tion and character of the folds, viz., at the part of the escarpment between 



LIX— Bull. Geol. Soc. Am., Vol. 1, 1889. 



