54 
It is now generally admitted that coal is of vegetable origin, having been 
formed under similar conditions to the peat bogs of the present day, the only- 
difference being that the vegetation was entirely different, so that however long 
the peats remain buried, and under whatever conditions they go, they will novel 
become bituminous coals, as the oily matter in the latter is due to the large quantity 
of resinous spores which fell from the great club mosses of the carboniterous 
period. 
True coal of the non-caking class has been found on the Collie River, anc ^ a *. H , 
of the carboniferous formation extends the entire length of the Colony; w u s 
brown coals, often of high quality, are found all round the South-West portion ox 
the Colony. 
ROCKS. 
A short Description of some of the Rocks most commonly met with in this Colony. 
The term rock, geologically speaking, is given to all the material which 
forms the earth’s crust, no matter whether soft or hard. Rocks are generally 
divided into two classes, sedimentary and igneous, but as many of the sedimentary 
rocks have been so much altered that they closely resemble the igneous, we will 
divide them here for simplicity, according to their composition, into fragmental 
and crystalline. The fragmental comprise all the unaltered sedimentary rocks 
which have been formed from the denudation of pre-existing rocks, the composi¬ 
tion of the new rock varying according to the composition of the rock which is 
being worn away and the condition under which it is deposited; when the finer 
particles, which would form mud, would be carried further than the coarse sands 
and gravels. This group of rocks also may bo said to include the limestone, as 
they have been derived from small particles of shell, coral, or the small calcareous 
shells of microscopic organism. 
The crystalline rocks may be either of igneous origin or have become crystal¬ 
line by long and continual heating without fusion; thus we find crystalline rocks 
with a well-defined bedding, proving them to be of sedimentary origin. 
Fragmental. 
Boulders are large masses of rock. 
Shingle , gravels, and pebbles are smaller, and rounded. 
Conglomerate may be composed of any of the former, cemented together. 
When the fragments are round it is called plum-pudding stone, and when angular 
breccia. 
Grit is composed of coarse sand and small pebbles, either cemented or loose. 
Sand is composed of fine silicious particles. 
Sandstone is composed of consolidated sand. 
Quartzite is a sandstone cemented by silica. 
Clay is a soft, more or less plastic, material, chiefly composed of silica and 
alumina, of almost every shade of colour from white to black. 
Shale is consolidated clay. It. has an uneven slatey structure, and is of many 
colours, but mostly dark. 
Slate is a stage further than shale, and is found mostly among the crystalline 
rock often graduating into mica schist, etc. It is a soft rock, and sometimes 
breaks into even slates or slabs, when it is of value for roofing and other purposes, 
but at other times it is massive. 
Alluvium is the earthy deposit made by running streams or lakes, especially 
during times of flood. 
