448 Geographical Collections. 
Geognostic Structure—The calcareous deposits which constitute the outline of 
the coast in the neighbourhood of Swan River, and which alternating with sands 
and sandstones, are met with forming almost perpendicular cliffs in the course of 
the river, appear to consist of two kinds. The first most ancient, though with 
every probability belonging to the tertiary formations, is that which presents the 
Most compactness, which alternates with sandstone, and is not very shelly. It 
forms the bluff headland at the mouth of the river, is the principal ingredient of 
the whole ridge lining the coast in the vicinity of this river, and is found near 
Geographe Bay lying on breciated conglomerates. It is every where pierced with 
caverns, sometimes crowded with stalactites. At Cape Naturaliste these attain a 
length of from twenty to twenty-five feet ; and in one case they presented the re- 
markable appearance of being all bent outwards, as if a gale of wind were perpe- 
tually blowing through the cavern. ‘This rock is a principle constituent of the 
Isle of Buache, where it is found alternating with sands in horizontal layers, and 
the hills formed by this mountain rock, instead of occurring in isolated summits, 
form long and continuous crests. ‘This formation is covered by a bed of sand 
mixed with the detritus of vegetables, which furnish the mould for the propega- 
tion of trees and shrubby plants. The second kind is a formation almost pecu- 
liar to the coasts of Ausiralia, and has been minutely described by Capt. King. 
Mr. Abel also noticed this formation at the Cape of Good Hope. “ It is impos- 
sible,” says Mr. Frazer, (Botanical Miscellany, Part If.) ‘‘ to pass along the 
beach fourteen yards without crossing a stream which issues from caverns of lime- 
stone, and which forms banks of shells, sea-weed, stones, and whatever substances 
may come in their reach, incrusting them in a beautiful manner.” Im the imme- 
diate vicinity of the sea, there occur downs which from this acticn are converted 
into extensive formations of mountain rocks; even far up the course of the river, 
the French described the limestone rock as entirely composed of incrustations of 
shells, roots, and even the trunks of trees. 
, Between the limestone rock and the Darling mountains cecurs a low tract of 
land of different structure,—a bed of large-grained sand covers a formation of 
compact clay of a reddish hue. ‘This change of structure is accompanied with 
other changes which we shall notice in the hydrographical part. 
At Cape Naturalisie there are immense clifis, presenting at their hase large 
beds of granite and schistose rock : large masses of feldspar were seen traversing 
those beds, in various directions, and of various thickness. The granite rock was 
ucceeded by a bed of micaceous schist, in an advanced state of decomposition, 
over which were observed several caverns, which were found to contain rock-salt 
in crystallized masses, and in large quantities. The base of the mountains (which 
were named Darling’s Range in hcnour of General Darling) is covered with frag- 
ments of quartz and chalcedony: the scil a red sandy loam. Farther up the soil 
improves to a light-brown loam ; but from its rocky nature is Incapable of culti- 
vation. 'The highest part of the range is of ironstone, and it is remarkable that 
there is no underwood. The island of Berthollet, distant six miles from Buache, 
is a barren, inhospitable spot, producing abundance of hares, seals, and mutton 
birds. Its shores present many tesselated clifis of limestone, resembling the tur- 
rets of a Gothic cathedral. 
FHydrography.—The most important features of the country are contained in 
the accessibility of its sheres, in the distribution of its rivers, and in the abun- 
dance of its fresh waters. ‘The entrance of Swan River was considered by the 
first navigators who visited this coast, as almost impossible during the prevalence 
of some winds, but the difficulties have been smoothed down by further acquain- 
tance, and the rocky, abrupt eritrence of this fine stream, appears, on the contra- 
ty, to offer some peculiarities of a very favourable description. In alluding to 
the hydrography of this district, it will be necessary to premise that the seasons 
are not the same as in our country. Spring occurs in September, October, and 
November ; summer in December, January, and February ; autumn in March, 
April, and May ; and winter in June, July, and August; and as the state of 
