BOTANY, CONCHOLOGY, AND GEOLOGY. 33 



marine shells, and this same feature has been met with 

 in digging wells in various parts of the island far from 

 this ridge.* 



It is thought that here may be a shell levee, similar 

 to that found at the Bahamas. If so, the relations of 

 the slopes would indicate just where the ocean was in 

 these ante-glacial ages. 



The projections called Great Point, Coatue, and a 

 part of Smith's Point are, according to the dame 

 authority, modern formations, composed of materials 

 torn from the island proper. It was probably before 

 the island had these two points of shelter — viz., Great 

 Point and Coatue — that the bluff was formed which 

 runs through the town separating Orange Street from 

 that part known as " Under the Bank " or Union 

 Street, which ridge extends to the North Shore. This 

 bluff, now covered with grass and habitations, so as to 

 be hidden somewhat from view, was once a mere 

 headland. 



Coskata, another drift mound, is separated from the 

 island by the Haulover, the latter dividing the upper 

 harbor from the ocean, — a portage for fishing boats, 



* In a letter written by Zaccheus Macy to the Massachusetts 

 Historical Society, dated at Nantucket, "y e 2<i y e 10 mo., 1792," 

 will be found these words : " And I have sent them a shell 

 taken out of my well thirty-nine feet below the face of the earth, 

 and I have taken many sorts of shells out of wells near forty 

 feet down. And one time when the old men were digging a well 

 at a stage called Siasconset, it is said they found a whale's bone 

 near thirty feet below the face of the earth, which things are 

 past our accounting for." 



