Page:A sketch of the physical structure of Australia.djvu/75

63 5th. Compact white quartz.

6th. A hard semi-columnar basalt, apparently a vein or dyke.

7th. A pinkish quartz rock.

8th. The same rock laminated and crystalline, and gradually becoming gneiss.

Thence, through Toodyoy, to a place called Bulgart, at that time the farthest inhabited spot towards the north-east in the colony, and about sixty miles from Perth, I found mention in my notes of greenstone, sienite, hornblendic and chloritic schist, gneiss and mica slate, with large intervening spaces of granite, with the details of which I shall not attempt to weary the reader. About three miles beyond Bulgart I was taken by Captain Sculley to the edge of the "sand plains," which were said to stretch to an unknown distance into the interior. These were plains of loose white sand covered with Banksia and other shrub-like trees and bushes, with bare sandy ridges rising at intervals. They much resembled the white sand plains of the coast, but the sand seemed more pure quartz, scarcely, if at all, calcareous, and the country was said to be hopelessly barren, utterly destitute of food except for a few kangaroos, and having only a few waterholes here and there known to the natives. From Toodyoy I rode up the Swan (here called the Avon) to York, and thence back by a different route to Guildford and Perth. In all the hill country I found the same rocks in similar variety with those previously mentioned.

I had carried a mountain barometer with me, and Mr. Roe, the Surveyor-General, was kind enough to make daily observations at Perth during my absence. By these means I was enabled to calculate roughly the heights above the sea of all the places I visited. I found I had never passed over any part much, if at all, exceeding 1,000 feet above the sea, but I also discovered that the bed of the Swan rose much more rapidly than I should have expected. From the coast nearly to the foot of the hills the river is affected by the tide. Where I first came down on it, on the road from Balup to Toodyoy, it was already 250 feet above the sea, having risen that height in a distance not exceeding twenty