100 Proceedings. 



regular layers. Chert does not belong to one geological 

 series only, but seems to be distributed in several. 



On this bed of impure limestone lies a bed of rock, called 

 the Base Bed, as forming the base or resting-place of the 

 freestone, known more particularly as Portland Stone. It is 

 a soft and wet stone, not so valuable as the rock resting 

 immediately upon it. Still ascending, we reach the best 

 Portland Stone, which is nearly white when dry, not so fit 

 for outdoor work as the layer above it, but very suitable for 

 indoor work and for statuary. The stone immediately above 

 is that which is most valuable for outdoor building ; it is very 

 compact and close-grained ; though soft when recently taken 

 from the quarry, it gets very hard on exposure. 



Over this lies a bed of stone of extreme hardness, composed 

 almost entirely of Oyster-shells, very useful for rough work, 

 and largely used in forming the breakwater ; but not avail- 

 able in Architecture, as it will not take a smooth surface ; so 

 hard is the stone that it has to be worked with a pick, like 

 Granite. Above this are a variety of beds of varying depth, 

 some yielding stone of inferior value ; the upper beds yielding 

 a stone of shaly nature, which seems to have been used at 

 one time in the island as roofing-stone. 



I must not, however, omit one bed of special interest, 

 called the Dirt Bed, which abounds with fossil trees, some of 

 considerable magnitude, plainly indicating that at one period 

 of the history of the island it was largely covered by forest ; 

 they are almost entnely trees of the Fir tribe ; some stumps 

 are left, rising a foot or eighteen inches into the layer next 

 above ; the pieces of one of these trees have been put 

 together, extending twenty feet ; some pieces I saw two or 

 three feet in diameter, and nearly as high. 



There are two dirt beds, bat one only contains fossil trees. 

 Very few trees are now found ui the island, and, except one 

 small plantation on the east side, it is really bare of trees. 

 The soil is fairly fruitful, being a mixture of clay and lime; 

 it grows good crops of Wheat in the south, and excellent 

 Potatoes. The island being very populous, few wild sea- 

 birds visit it, there being little shore and deep water all round, 

 except at the north and north-east sides. 



