62 J. D. Dana on the origin of some of the 



few yards of one another upon the coast, but above lugh tide level. 

 The large one contained, when recently opened by Mr. Frank Smith, 

 its discoverer, many large rounded stones. Another pot hole of less 

 depth exists upon Pot Island, about a mile to the southeast of Smith's 

 Island. It is like a bread-trough in shape, and is 4 and 2 feet in its 

 diameters, and 1^ feet deep. Still another, as I am informed, occurs 

 on Rogers' Island, one of the westernmost of the same group. It is 

 within reach of the tides and is 4 feet deep and 2 in width. These 

 pot holes must have been made by torrents from the land. For the 

 existence of such torrents the land should have been above its pre- 

 sent elevation. We cannot fix positively the era of this higher level, 

 but it may have been that of the great glacier, and the torrents, 

 sub-glacier streams then existing. 



c. The valleys of the streams of Connecticut and even those of 

 the north side of Long Island are in general continued over the bot- 

 tom of the Sound beneath its waters, apparently excavated for the 

 most part out of the sand and mud deposits which constitute it; 

 and this fact appears to indicate that the Sound was once dry land — 

 a great east-and-west depression of the surface — into which the streams 

 of the adjoining country flowed, and there concentrated their waters 

 in a grand central river which received the existing Connecticut a 

 few miles before enteiing the Atlantic. The admirable chart of the 

 Sound by the TJ. S. Coast Survey, which is covered with figures in- 

 dicating the soundings, enables any one interested in the subject to 

 draw the lines of equal depth, and verify this statement.* There 

 is nothing in the depth of the Sound to render the above supposition 

 incredible. An elevation of 100 feet would now lay bare all but a 

 fifth of its bottom across from New Haven, and one of 140 feet the 

 whole breadth ; and one of 200, would dry it up all the way to the 

 line of New London, 50 miles east of New Haven. Further, a rise of 

 even 50 feet would wholly separate the narrow western portion of the 

 Sound from the more eastern by a bare area in the meridian of Marm- 

 aroneck and Rye, or 50 miles west of New Haven. Only the broader 

 depressions corresponding to the courses of streams are to be looked 

 for over the bottom, even with the fullest possible series of sound- 



* It is best, in order to exhibit well on the map the curve of the deeper and shal- 

 lower parts of the Sound, to draw the hnes for each fathom of depth up to 8 fath- 

 oms, and then for every two fothoms, that is for 10, 12, 14 and so on; and in addition, 

 to make the lines for 7, 18 and 24 fathoms much heavier than the others; and to use 

 differently colored inks for the lines 4 to 8 fathoms, 10 to 22, and 24 and beyond; or 

 else give the areas 3 to 8 fathoms, 8 to 24, and over 24, different shades of color. 



