500 



SCIENCE. 



[N. S. Vol. XXIV. No. 616. 



pre-Pleistocene age and later than the Car- 

 boniferous bed-rock of the region. Similar 

 deposits are reported in borings elsewhere in 

 Boston and were noted by Crosby in his report 

 to the Committee on the Charles Kiver Dam. 

 Samples of this clay from the boring men- 

 tioned above were examined by the writer 

 in the office and compared with specimens of 

 various Quaternary, Tertiary and Cretaceous 

 clays, and were found to be almost identical 

 in appearance with much of the Cretaceous 

 clay from borings on Long Island described 

 by Yeatch and called by him Earitan. 



2. Unconformity. 



3. Very Ancient Till. — This was observed 

 at Lawrence and Haverhill, Massachusetts, at 

 Norridgewock, Maine, and at a few other lo- 

 calities. It is composed of a larger percent- 

 age of local material than are the common 

 tills of the region, is deeply oxidized, of a 

 brighter yellow color, and very rotten. A few 

 rounded pebbles of quartzite and similar du- 

 rable rocks are contained in it, but no granitic 

 or diabasic rocks could be found. These de- 

 posits are believed to correspond in age to 

 the old tills described by Fuller in south- 

 eastern Massachusetts, with the Mannetto 

 gravels described by Fuller and Veatch on 

 Long Island and elsewhere and with the Kan- 

 san or the pre-Kansan till of the middle west. 



4. Unconformity. 



5. Stratified Fossiliferous Clays. — Small ex- 

 posures of these beds underlie drunalins at 

 Winthrop and Revere, Massachusetts, and the 

 material derived from the clays, with its con- 

 tained fossils, is incorporated in the drumlins 

 of Boston Harbor. The deposits have been 

 correlated by Fuller with the Gardiner clay 

 of Long Island and Cape Cod. Local clays 

 which are possibly of this age have been ob- 

 served in Maine. 



6. A Thick Deposit of Till— This is the 

 principal till sheet of New England, including 

 hardpan deposits of sand, gravel, clay and 

 bowlders, often of great thickness, covering all 

 older formations. It includes the drumlins 

 of Massachusetts and New Hampshire. Where 

 it has not been eroded this till is yellowish 

 from the effects of oxidation to a depth of five 



to fifteen feet. Until recently it has been 

 considered of Wisconsin age, but Fuller has 

 lately thrown it into the Illinoisan, correlating 

 it with the Montauk of Long Island. The 

 evidence collected this summer of a more re- 

 cent till, confirms this correlation. 



7. A Great Thickness of Coarse Gravels. — 

 These are well developed in the Kennebec, 

 Androscoggin and Penobscot valleys, and their 

 relations are perhaps best exposed in the 

 vicinity of Augusta, where they may be seen 

 resting on (6) and overlain by (9) and (10). 

 They were deeply eroded before the deposition 

 of overlying deposits. These gravels may be 

 equivalent to the gravels described by Fuller 

 as overlying the Montauk till on Long Island, 

 etc. 



8. Unconformity. 



9. Fossiliferous, Stratified, Blue-Clay 

 {" Leda-Clay " of Jackson, Hitchcock, Pack- 

 ard and others). — This is an extensive deposit, 

 rising from about twenty feet above tide in 

 the vicinity of Boston, to over 200 feet in the 

 Kennebec and Androscoggin valleys and 

 found throughout the coast region and larger 

 valleys between Boston and Eastport. This 

 clay is well stratified, frequently fossiliferous, 

 and is deeply oxidized. It is occasionally 

 folded and contorted and often overlain by 

 sand deposits and generally by till. Fossils, 

 where found, most often occur near the bot- 

 tom of the clay beds, and stones are most 

 frequent in the upper part. The folding and 

 unconformity can be observed at Saugus and 

 Haverhill, Massachusetts; at Portland and 

 Augusta, Maine, and elsewhere. The pres- 

 ence of till both above and below the clay 

 places it most probably in the interval be- 

 tween the Illinoisan and Wisconsin glacia- 

 tions, and it may have been deposited at about 

 the same time as the lowan loess, to which its 

 relations are rather similar. 



10. Overlying the clay in some localities 

 are a few feet of stratified sands, rising to the 

 same general level as the clay, probably being 

 a part of the same series. These, together 

 with some of the Wisconsin sands, were called 

 ' Saxicava sands ' by the early geologists, 



11. Unconformity. 



