CHAPTER V 
The key of the past, as of the present, is to be sought in the 
present; and, only when known causes of change have been 
shown to be insufficient, have we any right to have recourse 
to unknown causes. HUXLEY. 
More about fossil plants. The relation between rocks and scenery. 
Rocks formed as sediment under water and rocks that are volcanic. 
Dykes of basalt. The loneliness of a Greenland beach. Deserted 
Settlements. 
ANY of the localities visited were on un- 
inhabited coasts where the land rose 
gradually inland for a few hundred yards; then the 
gradient rapidly increased up the face of the 
mountain. Deep ravines laid bare a succession of 
sedimentary strata 1000 ft. or more in thickness 
over which had been piled layer after layer of 
lava-flows and beds of volcanic ash (Fig. 34). 
Masses of frozen snow powdered with wind-blown 
sand or the darker dust from the shales were often 
met with in more shaded parts of the valleys. The 
widely spread sheets of basalt, in some places as 
many as thirty superposed layers, which give a 
terraced appearance to the weathered face of the 
cliffs like that on the rocks of Mull and other 
islands off the west coast of Scotland, are proof of 
long-continued volcanic activity on a stupendous 
scale. Another expression. of the same kind of 
phenomenon is seen in the numerous dykes which 
frequently cut across the beds of sandstone and 
shale. A dyke consists of some igneous rock, 
