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ISLAND LIFE 



PART I 



and the moraine matter will be distributed over a large 

 surface, so that the only well-marked token of its presence 

 will be the larger masses of rock that may have been 

 brought down. Such blocks are found abundantly in 

 many of the districts of our own country where other 

 marks of glaciation exist, and they often rest on ridges or 

 hillocks over which the ice has passed, these elevations 

 consisting sometimes of loose material and sometimes of 

 rock diffeo^ent from that of which the hlocJcs are composed. 

 These are called travelled blocks, and can almost always be 

 traced to their source in one of the higher valleys from 

 which the glacier descended. Some of the most remarkable 

 examples of such travelled blocks are to be found on the 

 southern slopes of the Jura. These consist of enormous 

 angular blocks of granite, gneiss, and other crystalline 

 rocks, quite foreign to the Jura mountains, but exactly 

 agreeing with those of the Alpine range fifty miles away 

 across the great central valley of Switzerland. One of 

 the largest of these blocks is forty feet diameter, and is 

 situated 900 feet above the level of the Lake of Neufchatel. 

 These blocks have been proved by Swiss geologists to have 

 been brought by the ancient glacier of the Rhone which 

 was fed by the whole Alpine range from Mont Blanc to 

 the Furka ' Pass. This glacier must have been many 

 thousand feet thick at the mouth of the Rhone valley near 

 the head of the Lake of Geneva, since it spread over the 

 whole of the great valley of Switzerland, extending from 

 Geneva to Neufchatel, Berne, and Soleure, and even on the 

 flanks of the Jura, reached a maximum height of 2,015 

 feet above the valley. The numerous blocks scattered 

 over the Jura for a distance of about a hundred miles vary 

 considerably in the material of which they are composed, 

 but they are found to be each traceable to a part of the 

 Alps corresponding to their position, on the theory that 

 they have been brought by a glacier spreading out from 

 the Rhone valley. Thus, all the blocks situated to the 

 east of a central point G (see map) can be traced to the 

 eastern side of the Rhone valley (led), while those found 

 towards Geneva have all come from the west side {p h). 

 It is also very suggestive that the highest blocks on the 



