THE AMERICAN MIDLAND NATURALIST. 



upper end a fresh water stream, Mill Creek, which is of 

 considerable volume, while both harbors receive at intervals 

 along their coast line smaller streams. In the outer harbor 

 above the entrance to Oyster Bay the water is uniformly 

 15-18 feet deep at low tide. Immediately below Oyster Bay 

 entrance is a bar with only 6-10 ft. of water at low tide. 

 At the eastern end of this bar is a channel 72 ft. deep. Out- 

 side of the bar the water deepens steadily toward the mid- 

 dle of the sound." 



The flora of the outer coast of the north side of the 

 island, of the quiet mud bottomed pools a hundred yards 

 back from the outer beach which are flooded at high water 

 by salt creeks, of the boulders scattered along the shores of 

 the harbor, of the quiet brackish areas near its inner end, 

 of the lakes at the upper end of the valley, of the springs 

 and pools on the edges of these lakes and the dense woods 

 surrounding them forms the basis of this list, to which 

 have been added the plants encountered on the excursions 

 of the botanical classes. 



Observations indicate that about four-fifths of the ordinary 

 shallow valleys lying south of the outer moraine have steeper 

 banks on the west than on the east side. A study by the 

 writer ('23) indicates that the cumulative effects of wind 

 and vegetation upon wind borne materials may explain this 

 in part at least. Exceptions appear, however, in the deep- 

 est valleys. Here the configuration depends on the curvature 

 of the streams. The erosion and cutting continue unto the 

 present day on the south shore where the water table comes 

 to the surface and supplies short streams with water. The 

 side slopes of the valleys are in large part steep and wooded 

 and are not now undergoing rapid change but storm waters 

 cut ravines in them, and springs here and there form gul- 

 lies and cause loose sand to flow out as quick sand. 



The south coast originally consisted of broad, lobelike 

 projections of sand and gravel since extended by the forma- 

 tion of marsh deposits. Some believe these lobes were 

 formed by the deposition of materials carried out by the 

 melting ice, and that the southern two'-thirds of the island is 

 thought to be made up of confluvial deltas from glacial 



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