Pkcember 5, 1902.] 



SCIENCE. 



915 



tlie international boundary in the treaty by 

 wliich it was defined. " The frontier line 

 shall run * * * along the most elevated 

 crests of said Cordilleras that may divide the 

 waters, and shall jsass between the slopes which 

 descend one side and the other." The Argen- 

 tines, therefore, claim that the line should 

 follow the crest of the Andes, crossing where 

 necessary the courses of those rivers which 

 flow throiigh the range; while the Chileans 

 claim that it should follow the water parting, 

 even when that would lead the line far out 

 upon the open pampas many miles east of the 

 mountains. The fact that mountain ranges 

 are sometimes cut through by the deep gorges 

 of through-going, transverse rivers was well 

 known as a general physiographic occurrence 

 at the time when the boundary treaty was 

 drawn up (1881), though the numerous specific 

 instances of this kind in the mountain range 

 in question had then been hardly recognized. 

 In spite of this want of local information, it 

 does not seem unreasonable to blame the 

 diplomats who drew up the boundary treaty 

 for being so careless with respect to complica- 

 tions of known possibility. They might have 

 learned a profitable lesson from the practice 

 of patent lawyers, who make so thorough a 

 defense of a new invention. The only dis- 

 turbing complications mentioned in the treaty 

 were those arising in valleys formed by ' bi- 

 furcation of the Cordillera ' where ' the water- 

 shed may not be apparent.' 



The maps, plates and text of the ' Report ' 

 give many details concerning the crest line of 

 the Andes, the deep gorges by which the moun- 

 tains are cut through, and the topography, 

 frequently morainic, of the pampas around the 

 headwaters of the through-flowing rivers. 

 These features have been described in abstract 

 in certain of the European geographical 

 journals, where at least one writer explains the 

 transverse gorges by the capture of eastern 

 drainage areas by the normal retrogressive 

 erosion of streams on the western mountain 

 slope. It is difficult to accept this explana- 

 tion, because it is not shown that the western 

 streams have enjoyed any advantage, such as 

 should have led them to acquire so much 

 drainage from their eastern competitors at so 



early a stage of mountain dissection as that 

 now reached by the Andes. Hatcher has sug- 

 gested, on the basis of his own observations, 

 that the peculiar river courses result from 

 relatively recent deformation of the region. 

 The aid that glacial erosion may have given 

 does not seem to have been considered, al- 

 though the possible sawing down of divides 

 by overflowing glaciers has elewhere been 

 showia to be an important process in heavily 

 glaciated regions. 



MAPS OF FAROE ISLANDS. 



The Danish General Staff has published 

 fifty-three sheets of an elaborate topograph- 

 ical map of what we tautologically call the 

 Faroe Islands. The map is printed in four 

 colors on a scale of 1:20,000, with contours 

 every ten (sometimes every five) meters. Only 

 the skeleton of what was originally a lava 

 plateau now remains. The larger islands are 

 divided into separate uplands by broadly open, 

 trough-shaped, through-going valleys that de- 

 scend with gentle slope in both directions 

 from a low valley-floor divide. The sounds 

 by which the islands are separated seem to be 

 only submerged valleys of the same kind. 

 Great cirques, from half a mile to a mile 

 across, open from the main valleys. The 

 strong slopes of the valleys and cirques are 

 notably smooth, unravined by the numerous 

 streams that descend from the uplands; and 

 hence it may be concluded that much of the 

 dissection of the lava plateau has been ac- 

 complished by ice action. If so, it is here, 

 as elsewhere, unsafe to infer postglacial sub- 

 mergence simply because some of the valleys 

 are drowned; for if glaciers can erode at all 

 they can certainly erode to a significant depth 

 beneath sea level. The sea-cut cliffs are very 

 bold on the western coast; those of Stromo 

 are 500 or 600 meters high at a distance of 

 only 200 or 300 meters inland from the shore 

 line. W. M. Davis. 



THE MAGNETIC SURVEY OF LOUISIANA. 

 Areangements have just been completed be- 

 tween Superintendent Tittmann and the State 

 Geologist, Professor G. D. Harris, for making 

 a detailed magnetic survey of Louisiana under 



