East Haven-£ra?iford Region. 363 



than three miles the eastern slope of the ridge is washed by 

 the lake, which is noted for the purity and depth of its waters. 

 Three-quarters of a mile from the northern end of the lake 

 and 300 feet from the western shore the Coast Survey found a 

 depth of 107 feet, and other depths nearly as great are recorded. 

 The surface of the lake is less than 15 feet above tide-level, a 

 height which is largely due to a dam. There are three main 

 curves in the range, with the convexity to the west and north- 

 west. The first extends from the southern end of the ridge to 

 the middle of the lake ; the second, from the latter point to 

 the crossing of the Branford-Foxon road ; the third, from that 

 point to the eastern extremity of the ridge. The whole ridge 

 forms a grand curve, convex toward the northwest, with its 

 chord, 4£ miles long, extending nearly northeast and southwest. 

 From its southern point to the railroad the ridge trends N. 10° 

 W.; north of the head of the lake the trend for two miles is 

 nearly east and west, while the eastern extremity bends around 

 to the south. 



This range consists of three distinct parts. The southern 

 portion has a general course of about N. 15° W., is rather 

 more than three-fourths of a mile long, and its highest points 

 are 140 feet above mean tide-level. At its southern end the 

 trap rises close to a ledge of granite from which it is separated 

 by low marshy land. Toward the north the trap tapers out 

 and the ridge decreases in height so that where it crosses the 

 New Haven-Branford turnpike the width of its horizontal sec- 

 tion is less than fifty feet, and it rises but thirty feet above the 

 sea. Here the rock is broken into small angular fragments 

 clinging loosely together, and is much decomposed. This is 

 what Prof. Davis calls trap " breccia " or a " brecciated struc- 

 ture," but the term seems to be misapplied ; for the rock evi- 

 dently is not sedimentary in origin, and its structure is due to 

 lines of fracture in the mass which have been made prominent 

 by decomposition. This portion of the ridge ends a few feet 

 north of the turnpike and is now separated from the second 

 part by the extremity of the lake, the waters of which conceal 

 the junction of the two parts. The second part begins about 

 ten feet north of the turnpike, at the dam, and extends some- 

 what more than a quarter of a mile west of north to a point 

 fifty or. sixty feet north of- the railroad (the Shore Line Divi- 

 sion of the ~N. Y., 1ST. H. & H. road), which makes a cut thirty 

 feet deep through the ridge. The hill rises to the height of 140 

 feet, and is surmounted by the stand-pipe of the New Haven 

 Water Co.'s works. This part, like the first, is precipitous 

 toward the west, and slopes more gradually toward the east. 



The third part of Pond Rock joins the second by a narrow 

 neck of trap, and, beginning forty or fifty feet north of the 



