516 F. P. GULLIVER — NANTUCKET SHORELINES 



an average of about 18 feet a year for the last fourteen years. The record 

 at this point has been pretty continuously kept, because the Life Saving 

 station has had to be moved back as the sea cut in. From measurements 

 made by the writer on the original plane-table sheets of the Coast Survey 

 it appears that the shoreline retreated 173 meters (567 feet) from 1846 

 to 1887. 



There appears to be a cutting back of the shoreline on the whole 

 southwestern coast of Nantucket from the west end of Miacomet fore- 

 land to the extreme western extension of Smith point, and also on the 

 southern portion of Tuckernuck island and Smith beach. This would 

 show that this great stretch of shoreline is being cut back on the western 

 side of Miacomet foreland the same way that on the eastern side there 

 is another great region where the sea is actively cutting back. Miacomet 

 foreland is an area of aggradation lying between two areas of retreating 

 shoreline. 



Two views are given taken from the top of the tower of the Life Saving 

 station at Maddaket. These were taken on September 6, 1903. The first 

 one is looking west toward Smith point and shows Tuckernuck in the 

 distance (plate 51, figure 1). A planetable map of this area is given in 

 figure 4. The second view is looking north from the Life Saving station 

 and shows the northern extension of Hither creek (plate 51, figure 2). 

 The southern end of Hither creek was shown on the first photograph. 

 In the distance on the second photograph Eel point is seen, and between 

 Eel point and the Maddaket houses in the foreground is Maddaket har- 

 bor. Hither creek, as seen in these photographs, is one of the many 

 valleys which cross the southern portion of Nantucket and which will 

 be discussed in a later paper. Many of these valleys now form ponds, 

 as Long pond, Hummock pond, etcetera. 



Origin of Valleys 



There are four hypotheses for the method of formation of these valleys 

 which the writer has considered in his study of the island. The first of 

 these is that the valleys were formed before the ice covered this region. 

 These valleys were, then, formed when the land stood higher than it 

 does at present, and were later covered with a comparatively thin mantle 

 of glacial waste, and then the land was depressed to its present position. 

 The second is that the valleys were formed in an interglacial period. 

 The third is that the valleys were formed during the time of the deposi- 

 tion of this glacial waste, and that they represent water channels when 

 the ice stood at the head of the valley. The fourth is that the valleys 

 were formed since the Glacial period. 



