Juke 17, 1910] 



SCIENCE 



931 



would not have been too geological, for 

 every point of the structural statement 

 bears helpfully on the appreciative under- 

 standing of the existing landscape, and 

 hence on its proper description. Nothing 

 is introduced simply for the sake of its 

 geological interest, however great that may 

 be; even the geological date of the strata 

 concerned is left unmentioned, because this 

 is geographically irrelevant. 



It may be noted in passing that the 

 terms coastal plain and coast plain have 

 been used by some geographers to designate 

 platforms of marine abrasion, now uplifted 

 so as to form a littoral lowland. Geograph- 

 ical terminology is so little developed and 

 systematized that no agreement as to the 

 limitation of these and various other terms 

 has yet been reached. 



Although a marine coastal plain is in its 

 earliest youth a smooth surface, gently in- 

 clining from the oldland to the sea, the first 

 sentence of the description given above 

 includes the significant word, dissected; 

 and with this the reader must immediately 

 pass from the conception of the initial 

 stage of a smooth coastal plain to the later 

 stage of a surface made uneven by the 

 erosion of many valleys. The strata that 

 form the plain are said to be unconsoli- 

 dated, and this suffices to exclude all out- 

 cropping ledges from the present land- 

 scape, particularly as the dissection of the 

 plain is said, in the second sentence, to 

 have reached a late mature stage. All the 

 hill slopes must therefore be conceived as 

 cloaked with a creeping soil. The former 

 shore line, marking the original inner bor- 

 der of the plain, must have lost whatever 

 distinctness it may have had at the time of 

 uplift; and it is indeed to-day hardly to 

 be detected. 



For similar reasons, all the streams must 

 be conceived as having thoroughly well- 

 graded courses, and all but the smallest 



valleys must be pictured as having fiood 

 plains of gentle fall. The general pattern 

 of the streams and their valleys is suffi- 

 ciently indicated by the words, prevailingly 

 consequent and short insequent. These 

 must be taken to mean that the larger 

 streams flow almost directly to the sea in 

 sub-parallel courses about at right angles 

 to the general trend of the plain as a 

 whole; while many small valley-heads 

 branch in various directions from the trunk 

 valleys. The hilly interfluves between the 

 chief valleys must, in a late mature stage, 

 be pictured as having lost something of 

 their initial altitude, and hence, when 

 looked over in the direction of the length 

 of the plain, as no longer rising to a per- 

 fectly smooth and gently sloping skyline, 

 but nevertheless as approximating to this 

 form ; while the spurs that branch from the 

 axes of the interfluves must be pictured as 

 generally pointing toward the sea and as 

 descending by gentle, graceful and well- 

 graded slopes into the open valleys. The 

 texture of dissection being described as 

 rather coarse, the hills and spurs must be 

 conceived as having contour lines in flow- 

 ing curves of rather large radius; and all 

 close-set, sharp-cut ravines must be ex- 

 eluded. 



At a late mature stage, the larger ex- 

 tended rivers must of course be pictured 

 as having broad valley floors; and the sea 

 must be imagined as having cut back or 

 retrograded the front border of the plain, 

 so that the sea-board hills are evenly trun- 

 cated in a long succession of sea cliffs, all 

 standing in accordant line over a well- 

 developed beach. Deltas must be absent. 

 The general picture thus sketched must 

 then be slightly modified by terracing the 

 main valleys and by widening or pro- 

 grading the beach into a well-developed 

 strandplain. 



The technical terms here employed are 



