44 ARCTIC BASALT PLATEAU 
easily visible and its conformity with the valley direction is not 
difficult to. establish. This matter of fact may awake the thought, © 
that the basalt streams follow ancient river beds, the rapid broadening 
of the valley downstream immediately out of the basalt region giving 
some support to this thought. The parts of the valley cut in the 
basalt are in some sense antecedent. 
li the thought developed above were true, the deepseated broad 
canon-shaped valleys may have been cut down through the basalt 
measuring in some parts 300 metres and more of thickness, that 
being the depth of some valleys and such a mighty outfilling of 
the valley might seem improbable. The question arises, why did 
the river course not change passing in the casing, less resistant 
calcareous sediments? ; 
Previous explorers have certainly reported that the basalt series 
were composed of a number of separate flows, crowded one upon 
another with astonishing regularity and of various thickness; that it 
often happens, that the crowning flow is accompanied in lower level 
by a parallel intrusion sheet (or sill) of constant thickness, the verti- 
cal distance between the capping basalt-bed and the sheet being 
almost constant too.' The massiveness of the sedimentary series. 
may let such a constancy appear astonishing. The old name „trapp“ 
= staircase) for siberian basalts suggests also a parting in a number 
of separate flows. In this case it seems probable that the flows may 
have poured one upon the other, the lowest being the oldest and 
the topping bed the youngest. 
In broader parts of the valleys this partition in mighty flows is well 
developed and the niveau of each flow persists in horisontality and 
great constancy, the surface of each of them forming terraces. The 
shapes of these terraces reminds one from a distance of waterborn 
raised beaches, and this resemblance leads the thought to updammed 
lakes with elevated shore lines. The most remarkable fact is that while 
1 An apparent geological structure of identical character was tested also by the 
writer. 
