FLORA OF BATHURST. 469 
luxuriantly, it would indicate probable Serpentine in the imme- 
diate neighbourhood. Similarly, in the valley of the Thames, one 
can often predict an outcrop of London clay by seeing a clump of 
large trees, elms or oaks, growing together, since those trees are 
not nearly so common on the subjacent lower London Tertiaries. 
PHYSIOGRAPHY OF BATHURST. 
Tn order to understand some of the peculiarities of the Bathurst 
flora, a brief account of the physiography of the district may be 
given. The city of Bathurst is at a height of about 2,200 feet 
above sea-level, and is at the centre of a tract of undulating country 
known as the Bathurst Plains. At a distance of about 10 
miles from the city, hills rise all round the plains, and reach a 
height of from 1,000 to 2,000 feet above them. ‘The climate is 
generally dry, with a moderate but very variable rainfall, ranging 
from 15 to 34 inches in the year. There are considerable fluctu- 
ations in temperature, the average daily range being greater than 
that of almost any other place in New South Wales. The winters 
are of moderate severity, the temperature sometimes falling below 
20° F. for several nights in succession, while the summer tempera- 
ture may reach 105° in the shade. The rainfall is irregularly dis- 
tributed throughout the year. Under these conditions, it need 
hardly be said that the flora is essentially different from that of 
the coastal districts of the colony, with their equable temperature 
and heavier rainfall, and one would not expect to find it very rich 
or varied. Geologically, there are three distinct formations within 
the district. These are—1l Granite, 2 Silurian, 3 Devonian. 
The whole of the plains is included in the granite area. In 
places the granite is covered with beds of drift gravel, and in the 
immediate neighbourhood of Bathurst there are hills—-Bald Hills, 
Mount Apsley, Mount Pleasant—capped with basalt. The Bald 
Hills form by far the most extensive of these outliers of basalt, and 
certain plants occur there which have not been found on the granite. 
The granite itself is much decomposed over most of the area, but 
compact veins and bosses occur in places, and the rock is there seen 
to be made up of quartz, felspar, black mica, and hornblende, with 
accessory minerals, such as apatite, sphene, and others. Near the 
boundary the character of the granite changes somewhat, especially 
on the west of Bathurst. This change in the granite seems to be 
accompanied by a change in the flora which is richer there than 
over the rest of the plains. Silurian rocks form most of the hills 
which surround the plains. They consist of slaty and schistose 
rocks, with beds of limestone in places. Quartz reefs are not 
uncommon and mineral veins of various kinds also occur, including 
some of copper ore which have been worked to a considerable 
extent. Silver ores are also found at several localities, 
