PHYSIOGRAPHY. J 



represent the Tertiary dissection of the uplifted Cretaceous pene- 

 plain, whose upland remnants constitute so important a share of 

 the topography of the Atlantic slope. 



Submergence of the valleys produced the ragged coast of Maine, 

 the depression being associated with the glacial epoch ; but since 

 then there has been an emergence of at least 300 feet, as may be 

 proved readily on this excursion. During the period of subsidence, 

 postglacial marine clays were deposited in the arms of the sea and 

 are to be seen now in the valleys, where they form flat fields dis- 

 sected by a young drainage system, with narrow valleys and fre- 

 quent landslides. The shore line of the 300-foot level may be rec- 

 ognized in a bench and bluff at the southeast base of Blackstrap 

 hill, and again at Poplar hill, another drumlin three miles farther 

 north, as well as on certain beach-like gravel flats, north and south 

 of the latter. The present ragged shore line of Maine is therefore 

 not the direct result of the submergence of a rugged land, but of 

 the emergence of an uneven sea bottom — uneven because the ma- 

 rine clays that were spread upon it had not been deposited in suf- 

 ficient quantity to smooth over its previous inequality. 



The farmers of the coastal district make a division of their land 

 on a strictly physiographic basis. The ledgy ridges are left to 

 forest, wood lots, and rough pastures. Ridges of this kind ad- 

 vance between the clay-filled valleys toward or to the coast line ; 

 outlying ridges or hills form the island fringe off shore. Till-cov- 

 ered uplands are generally cleared and farmed, as north of Black- 

 strap hill; here stonewalls often divide the fields. The clay-filled 

 valleys are cleared and cultivated ; the roads are very bad in wet 

 weather, unless improved with gravel. Farmhouses are located 

 frequently close to the line between ledgy hills and clay fields. 

 Often streams are superposed locally on ledges once buried by the 

 clays ; hence waterfalls are common near the shore line, and this 

 feature gives reason for the occurrence of paired cities, like Lew- 

 iston and Auburn on the Androscoggin, and Saco and Biddeford 

 on the Saco. 



A comfortable trip from Boston to Portland and back may be 

 made by boat at night ; and the day between will suffice to give a 

 good view of the coastal district, especially if a bicycle is taken 

 along, and the roads are not rough and muddy from recent rain. 



Literature. 



There is no literature upon this subject, from the standpoint pre- 

 sented here. 



