238 Phytogeographical. 



slope has here a declivity of 34° to 3()° the average slope in 

 other places being 67° to 7N°. 



The bottom of the crater is in general tolerably Hat but uneven 

 on account of the numerous pieces of rock that have fallen 

 down from the sides. The whole surface is covered with a, bed 

 of humus. 



The fragments of rock that have served in the structure of the 

 crater are for the greater part Augite— Audesite only here and 

 there occurs Hornblende— Augite— Andesite. 

 The Quill is bordered on all sides by very steep, not seldom per- 

 pendicular rocks. The browns ot these rocks form a ridge which 

 has a width of only a few m. and the height of which varies 

 between 391 and 581. On the outside the slope of the hill is 

 at first, in general, very steep, but it is gradually declining to 

 shelve away at last in a plain in a northwestern direction 

 or to be suddenly cut off by the steep sea coast. On the southern 

 side only inaccessible rocks called the White Wall, which with 

 a declivity of 45° rising from the sea disturb the regularity of 

 the profile of the mountains. 



The second group of mountains taking up the N. W. part of the 

 island consists of a great number of hills of which the highest 

 called „Boven" has a height of 295 m. 



The very steep coast that begins near Heiligenbaai bordering 

 the further northern side of the island, is formed by a gigantic, 

 perpendicular wall of lava (Augite— Andesite.) 

 By a deep ravine Boven is separated from Gilboohill. This hill 

 174 m high, is formed partly from ashes and partly from solid 

 volcanic matter. The other hilly ground consists out of a num- 

 ber of more or less sharp tops which are connected by a ridge. 

 This ridge runs close to the seashore from Boven to Tumble- 

 downdickbay and extends from there in eastern direction as 

 far as Mary Glory, the highest top of the range. Going east- 

 ward from there we perceive that the ground is considerably 

 sloping. 



To the northern hills of St. Eustatius belongs also a crater, the 

 exact form of a horse shoe lying south of the Tumbledowndick- 

 bay and facing the town. The highest eastern top of this crater 

 is Signalhill (226 m.) the northwestern one is called Pilothill. 

 As to petrography the northern part of St. Eustatius offers but 

 little variety; the mineral most occurring is Augite— Andesite. 

 Almost the whole northern part of the island is covered with a 

 kind of good humus, produced from volcanic ashes mostly mixed 



