U'2 



THE VOYAGE OF H.M.S. CHALLENGER. 



fragments of magnetite, augite, felspar, and glassy fragments, and when a large quantity of 

 the rock of Bermuda is dissolved away with acid, a small number of fragments are also 

 met with. These mineral particles most probably came originally from the. pumice 

 which had been cast up on the island for long ages (for it is known that these minerals 

 are present in pumice), although possibly some of them may have come from the volcanic 

 rock, which is believed to form the nucleus of the island. 



The land surface of the islands is almost entirely composed of blown calcareous sand, 

 more or less consolidated into hard rock. In several places, and especially at Tuckerstown 

 and Elbow Bay, there exist considerable tracts covered with modern sand dunes, some of 



Fio. 56. — " Sand-Glacier " overwhelming a garden. Elbow Bay, Bermuda. 

 (Fro?n a Photograph.) 



which are encroaching inland upon cultivated ground (see fig. 56), and have overwhelmed 

 at Elbow Bay a cottage, the chimney of which only is now to be seen above the sand (see 

 fig. 57). The constant encroachment of the dunes is prevented by the growth upon 

 them of several binding plants, amongst which a hard prickly grass (Cenchrus), with 

 long, deeply penetrating root-fibres, is the most efficient. When these binding plants 

 are artificially removed, the sand at once begins to shift. 



The scenery of Bermuda is in some respects not unlike that of certain northern lake 

 districts, for the numerous small islands which are dotted over the sounds and land-locked 

 sheets of water are covered with vegetation down to the water's edge. The dark colour 

 of the Juniper (Juniperus bermudiana, a species peculiar to these islands and the West 

 Indies), called in the island " Cedar," the prevailing foliage, not unlike that of Pines in 

 appearance, gives the landscape a northern aspect, and on cloudy days, the island, as 

 viewed from the sea, looks cold and bleak. The extreme lowness of all the land, however, 



