492 PROCEEDINGS OP THE NEW YORK MEETING 



The next paper was entitled : 



THAMES RIVER TERRACES IN CONNECTICUT 

 BY F. P. GULLIVER 



Dana classed the terraces on the sides of the drowned valley of the Thames river, 

 Connecticut, as fluviatile deposits of the Champlain period, and thus considered 

 that they were formed as floodplains in a greatly expanded river, their summits 

 marking the greatest height reached by the floods from the fast melting ice-sheet. 

 The writer has for some time considered the above hypothesis inadequate to ac- 

 count for the many forms assumed by the glacial waste at levels intermediate be- 

 tween the upper terrace and the present bed of the Thames river, particularlj^ those 

 typical eskers which today lie partly submerged in the waters of the estuary. Not 

 until the recent cuts, made for the new line of the New York, New Haven and 

 Hartford railroad in eastern Connecticut, along the east bank of the Thames river 

 between Norwicli and New London, had revealed the delta structure of these flat- 

 topped deposits lying against the stee^:) sides of this valley, which had been devel- 

 oped to adolescence before the depression of the land took place, was it possible to 

 make out a more detailed history of the aggradation which occurred in this valley 

 in Pleistocene time. The present paper outlines more in detail the method of this 

 deposition. 



The first question testing the flooded river hypothesis is whether these deposits 

 form a uniform grade, rising gradually higher farther and farther upstream. 

 Roughly, this is the fact. The terraces rise 10 to 15 feet above the river at New 

 London and increase in height up the river until they are 90 to 100 feet above tide 

 at Norwich. These level-topped deposits are not continuous, however, and a series 

 of accurate levels run up the river might show that these deposits belong to more 

 than one system and do not fall into one grade.* 



At several points along the river there are typical eskers which do not rise to 

 the level of the flat-topped deposits. These present to the eye the characteristic 

 ridge, with steep sides and curving first to the right and then to the left, which 

 has generally been recognized as a constructional form produced by glacial rivers 

 at a late stage in the melting of the ice. A very good example is found about 3 

 miles below Norwich, on the east side of the river, opposite the little Indian vil- 

 lage called Mohegan. The unsubmerged portion of this esker has been used by the 

 railroad, as a part of its embankment, in crossing one of the numerous coves which 

 resulted from the drowning of the Thames valley. The summit of this esker is in 

 places more than 80 feet beneath the level of the gravel plain less than a mile to 

 the north. This gravel ridge has the typical constructional esker form, as if the 

 glacier had left it but a few weeks ago ; therefore it is very difficult to conceive 

 that a flooded river could have built a floodplain 80 feet above this deposit with- 

 out obliterating its ridge-like form. 



Two miles above the United States naval station there was another short esker, 

 some 30 feet below the level of the terrace at this point on the river, which has 

 been almost entirely removed by the engineers to fill in across one of the deep side 

 valleys. The bottom at this place was found to be covered with very fine mud, 

 which slid to one side when rock and gravel were piled on top, so that a great deal 



*See paper by F. B. Koons, Am. Jour. Sci., 1882, p. 425. 



