178 



SCIENCE. 



[N. S. Vol. I. No. 7. 



THE GEOGRAPHICAL EDUCATION OF OUE 

 TOPOGRAPHERS. 



Some engineers hold the opinion that it 

 is not necessary for a topographer to have 

 an understanding of the forms that he maps ; 

 it is sufficient for him simplj^ to record what 

 he sees without knowing its meaning. If 

 all topographers could sketch with minute 

 accuracy, if thej' all worked on a large 

 scale and without limitation of time, they 

 might perhaps manage to get along without 

 an appreciative knowledge of the subject of 

 their sketching. But the topographers by 

 whom our maps are made cannot as a rule 

 sketch with minute accuracy ; and even if 

 they could, their talent would be of little 

 avail, for time could not be given to its use; 

 moreover, maps of a scale large enough for 

 minute accuracy are too expensive to un- 

 dertake in so vast a country as ours. In 

 many parts of the country the land is 

 hardly worth as much per mile as it would 

 cost to map it in an elaborate manner. 

 Our maps must be made on a relatively 

 moderate scale — seldom more than an inch 

 to a mile ; expensive detail cannot be per- 

 mitted ; and very slow work must give way 

 to methods that will give results more 

 rapidly. A great deal of our topographical 

 work must be done by rapid sketching be- 

 tween measured points ; the sketching must 

 always be generalized ; and every thing 

 that will promote the production of good 

 results from rapid and generalized sketch- 

 ing must be taught to the topographer. 



Looking at the subject in this practical 

 manner, there can be no question that an 

 appreciative understanding of topogxapM- 

 cal features is of great value. Eapid work 

 by a topographer who does not understand 

 the country before him will produce an un- 

 appreciative portrait. Generalizations bj' 

 a surveyor who does not understand the 

 relations of the forms that he generalizes 

 wUl produce an unsuggestive and inaccur- 

 ate map. . A good understanding of physio- 



graphy should therefore be regarded as an 

 essential qualification of a topographer ; and 

 schools of engineering should see to it that 

 adequate teaching of this subject is pro- 

 vided for theu" students. 



WINSLOW'S EXPLANATION OF THE MISSOtJKI 

 PLAINS. 



Such an alternative hypothesis is offered 

 by A. Winslow in his recent report on the 

 lead and zinc deposits of Missouri (Geol. 

 Survey of Missouri, Vol. YI., 1894). He 

 describes certain parts of southern Missouri 

 as exhibiting broad expanses of nearly flat 

 land. A ' prominent feature ' of the district 

 is ' the steepness of the hills adjacent to the 

 stream valleys' (p. 306). Another part 

 of the same region is a dissected plateau of 

 carboniferous strata, terminating eastward 

 in an irregular escarpment. The even inter- 

 stream uplands of both plain and plateau 

 are not regarded as of constructional origin, 

 for the region has long been above sealevel ; 

 the possibility of either upland having once 

 been a smooth peneplain of baselevel erosion 

 is considered and rejected ; and the follow- 

 ing hj'pothesis is offered in its stead : 

 " These prairie and plateau plains are pri- 

 marily due to the fact that the slope of the 

 surfaces has alwaj^s been and continues 



slight Consequently, the flow of the 



streams has been so sluggish that general 

 atmospheric degradation has nearlj^ kept 

 pace with the corrasion of the streams and 

 formation of the valleys. As a result, the 

 whole surface has been denuded simultane- 

 ously. This condition is attributable, first, 

 of course, to the gentleness of the original 

 constructional slope ; the horizontality of 

 the stratification has helped to perpetuate 

 it Secondarily as a factor in the pro- 

 duction of these surfaces, it is probable that, 

 where streams have con-aded so slowly, 

 broad flood plains have been developed at 

 difierent levels at diiferent times. Thus 

 many flat stretches, which may be removed 



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