A STUDY IN CONTRASTS 93 



pressive example of intrusions of igneous rock is 

 afforded by vertical walls of basalt which stretch 

 across the valley. These magnificent dykes do not 

 form continuous curtain walls from one side of the 

 valley to the other, but the rocks are twice or 

 thrice stepped on each side; the light brown wall 

 of basalt towers against the sky at least 100 ft. 

 above the upper level of the slope of the ravine. 

 Its jagged and weathered ledge projects horizon- 

 tally for some distance towards the middle of the 

 valley and is then cut vertically down into a deep 

 step, and this is repeated two or three times. At 

 the foot of the valley the dyke crosses the stream as 

 a resistant barrier where the water falls in a cascade. 

 The ravine at Atanikerdluk (Fig. 46) stirred the 

 imagination more than most of the many impres- 

 sive scenes in other parts of Greenland. To anyone 

 interested in geology a sense of sharp contrasts 

 between the present and the past is so constantly 

 evoked by the interpretation of the rocks that the 

 wonder of it becomes less intense; but there are 

 places and circumstances in which this sense of 

 change from one age to another is awakened with 

 especial force and vividness. The icebergs floating 

 on the arm of the sea, a thousand feet below the 

 ravine, are fragments of the shield of ice that has 

 lain for thousands of years over nearly the whole 

 of the interior of the country; the clumps of Arctic 

 plants on the sloping banks of weathered sand- 

 stone on either side of the glacial stream are in 

 harmony with the climatic conditions of the present 

 moment of geological history. The waifs and strays 



