138 KOSS ON PAKALLEL LINES OF ELEVATION. 



which would be the pole of another great circle perpendicular to 

 those of the systems, but that for short distances the arcs referred 

 to may be considered as parallel. 



The defect of this admirably simple and complete theory is that 

 it is not in accordance with the facts. / confess some astonish- 

 ment, too, at his getting his nineteen European systems to conform 

 to it. The circumstance that gives it a certain value is that the 

 axial lines of the chief lines of elevation intersect each other in the 

 neighborhood of the two great Archipelagoes. 



As ;^ rule the regions in the vicinity of the axial lines of zones 

 or subzones of elevation are slowly rising, and the depressed 

 regions between them are undergoing still further depression. This 

 process may be best observed in Australasia and Polynesia , where 

 the coral rocks and islands may be said to preserve a record of the 

 changes of elevation m regard to the sea-level. It seems to result 

 from lateral pressure in the earth's crust caused by a shrinkage of 

 the liquid interior from loss of caloric. 



In describing the zones and pointing out the locality of their 

 axial lines, it will be remembered that I found theM^*, as a. rule, to be 

 on the southerly side of the continents — the apparent development 

 of the zones being on their northerly sides. This in connection 

 with the greater intensity of the plicating forces in the vicinity of 

 the axial lines, explains why the southerly slopes of the continents 

 are steep and abrupt, with high mountains near the sea, and deep 

 sea near the land, and aifording many peninsulas and islands. But 

 where in exceptional cases, as South America and Africa, there is 

 an axial line (zone No. 3) extending along or near its northern 

 part also, we find a rapid and abrupt descent from the Venezuelan 

 coast range and the Atlas mountains, to the remarkably deep 

 Caribbean and Mediterranean seas, characterized by Archipelagoes. 



As the lines of elevation of zones ISTos. 1, 2, 5, 7, have their 

 intersections with the equator at an angle of approximately 45 deg. 

 it follows that within some fifty degrees on each side of the equator, 

 very many of the more important lines of elevation have the direc- 

 tions of north-east or of north-west (approximately) ; and as the 

 lines of elevation of zone No. o are approximately east and vv^est, 

 and those of the other two zones — Nos. ^ and 5 — ^^intersect the 



