Prof. Nordenskiold — Expedition to Greenland. 365 



Fig. 6, but which a couple of years later filled the whole of the 

 harbour lying before it, and is now terminated in the manner shown 

 in Fig. 5. 



The great denuding effect of the glaciers has been, as is known, 

 proved by numerous and accurate investigations. Greenland also 

 offers examples of this in the long and deep fjords that indent its 

 coasts, and which, if they run parallel to ante-glacial depressions of 

 the earth's crust, yet, as the smoothed, scratched and grooved rocks 

 and the erratic blocks strewn high up upon the slopes show, have 

 been widened, formed, and cleansed from earth, gravel-beds, and 

 looser sedimentary mountain detritus by the operation of the glaciers. 

 The mere effect of the immovable inland ice cannot be any thing like 

 so great. Nevertheless, here also the earth and the layers of gravel are 

 completely washed away by the rapid glacier streams running under 

 the ice. The subjacent original rock is thus exposed, and perhaps to 

 some extent worn away, especially in places where the ice passes over 

 layers of limestone, sandstone, or slate. Its original depressions, filled 

 during the older geological periods, therefore re-appear, and often 

 form — when the ice covering has again retired — the basins of those 

 beautiful lakes which characterize all glacial lands. To assume that 

 the whole lake-basin has been scooped out during the glacial period 

 is, however, evidently a mistake ; and equally erroneous is the form in 

 which it is customary to clothe the theory of the origin of Alpine 

 lakes. But when we take into consideration how rapidly (even 

 within historical periods) a lake is filled and converted — first into a 

 morass, and then to a level and dry plain — we easily see the reason- 

 ableness of the following proposition : 



We meet with lakes only in those places where, from some cause 

 or other, during the latest geological periods, depressions or ex- 

 cavations have taken place in the crust of the earth ; and since, 

 among more generally operating causes than this, we know only 

 of the volcanic and glacial powers, it is natural to conclude that 

 modern (not filled up) lake-basins only occur where the strata, in 

 consequence of volcanic activity, have fallen in, or where the ice 

 has ground to powder, and the glacier-streams have swept away, the 

 looser earth and rocks situated nearest to the surface of the earth. 



On observing Tessiursarsoak from the heights nearest to the spot 

 where we had first descended from the glacier, we had perceived that 

 its appearance had changed in a remarkable manner ; its surface was 

 bright as a looking-glass, and so thickly covered with ice that our 

 first impression was that we had an arm of the inland ice before us. 

 On arriving at the tent we discovered the cause of this. Daiung our 

 absence the inland ice had launched or deposited ice in such quantities 

 that the whole bay was almost choked with it, and the Greenlanders 

 were very uneasy, for fear partly of our being inclosed, and partly of 

 the violent waves caused by the deposition. They were therefore 

 very glad when, immediately on our arrival at the boat, we declared 

 our readiness to start on the following day. 



In order to be in time to meet the Inspector — who just at this time 

 was expected to visit the colonies around Disko Bay in a commodious 



