AGASSIZ : BAHAMAS. 55 



The vegetation of Andros consists mainly, as I was informed by Mr. 

 Chamberlain, of pine, mahogany, mastic, aud the heavy undergrowths. 



The ridge which runs parallel or nearly so to the coast is followed by 

 a second ridge from forty to sixty feet high, separated from the first by 

 a wide flat plateau, beyond which we come, by a rapid descent about five 

 miles inland, upon the low flat land which extends to the western edge 

 of the island and forms the marl shores we visited at Wide Opening. 



Morgan's Bluff (Plate XXXIII.) has the finest limestone cliffs on the 

 eastern face of the island. The outlying islands and rocks and islets off 

 the east coast of Andros, of which High Cay is a good example, as far as 

 the South Bight, are all of seolian origin, and have been separated from 

 the main island by the same agencies which have been at work in other 

 parts of the group. The seolian rocks of Andros itself differ in no way 

 from those of other islands. The eastern edge of Andros is separated 

 from the deep water of the Tongue of the Ocean only by the narrow 

 shelf of the bank of which the eastern edge is occupied by the long bar- 

 rier reef which protects the eastern edge of Andros, leaving an excellent 

 well protected inside channel for small boats along the whole length of 

 the island. 



From Andros to Orange Cay. 



From Billy Island we steamed across the northern end of the great 

 white marl belt forming the southern edge of an excellent sponging 

 ground which extends northward towards the edge of the Bahama 

 Bank, south of the Northwest Providence Channel. The white marl, 

 as we stopped to dredge or to sound, seemed very barren of animal 

 life. Here and there an occasional sponge could be seen. On our 

 way to Orange Cay we found that the white marl as we got farther 

 west gradually contained more coral sand, which became coarser and 

 more abundant as we approached the western edge of the bank, where 

 the bottom was again composed of the characteristic coral and seolian 

 sand found upon other parts of the Bahama Bank. With the in- 

 crease of the coral sand we came upon a species of Thalassia with huge 

 roots, by which it anchored in the fine marl. The great development of 

 the roots is very characteristic of the coralline algae, which thrive upon 

 the coral sand bottoms. A macroscopic examination of the marl from 

 the shore of Billy Island showed that it contains a good deal of vegetable 

 matter and a few Foraminifera, an indication most probably that the marl 

 was formed in a lagoon with free access to the sea, perhaps a sink much 



