Part 21

We all arrived safe at the hospitable residence of Mr. W. Burges, on the Irwin; the following day being occupied in making up the accounts connected with the expedition, which, including the whole of the cash expenditure, did not exceed 40 pounds, which sum had already been subscribed by a few settlers interested in the undertaking.

Quitting the Irwin on the 1st of July, and proceeding by way of Dandaragan and Toodyay, I arrived, with Mr. Roe and chainer Fairburn, in Perth on the 10th instant, having accomplished a journey of nearly 2000 miles in 107 days.

On reviewing the foregoing report, I find it necessary to add a few observations on subjects that could not well be introduced into the body of the narrative.

GEOLOGY OF COUNTRY.

In the first place, viewing the geographical and geological features in combination, the tract of country contained within the 114th and 118th parallels of longitude, and the 24th and 27th degrees of south latitude, may be considered as an inclined plane, the eastern edge of which has an elevation of about 1700 feet above the level of the sea. Commencing from the coast, the first 100 miles is almost exclusively of tertiary sandstone formation, which the process of denudation has, in many instances, converted into either stony or sandy tracts, rarely fertile, except when subject to the influence of frequent inundation. This region seldom gives rise to rivers or watercourses; the flat-topped ranges, which are often found towards the eastern limits of this formation, do not generally exceed 500 or 600 feet in altitude, and are only those portions of country that have not as yet yielded to the waste of time, or the constant action of rivers, which, rising in the higher lands more to the eastward, rapidly abrade, and in their onward course remove the soft and porous sandstone from their bases.

In the deeper valleys, towards the eastern edge of these sandstones thin beds of oolitic limestone, containing numerous fossil shells, occasionally occur; also gypsum and clayey shales, with other indications of the probable existence of coal in the vicinity; following the series appears a compact, fine-grained amorphous sandstone, having an almost flinty fracture; this rock, in a few miles, gives place to granite and gneiss, frequently broken up by the upheaval of whinstone and porphyritic trap hills, having an elevation of from 100 to 500 feet above the plain.

As we proceeded eastward, the eruptive rocks became more numerous; chlorite slate, veins of quartz, chert, and variegated jasper, frequently forming the summits of the most elevated hills, while, on the general level of the plain, are occasionally found thin beds of ancient lava.

The rivers, unlike most others in Western Australia, have nearly an even fall throughout their entire length, amounting on an average to six feet per mile; this, in a country subject to the sudden fall of almost tropical rains, is what gives rise to the destructive inundations already described.

CLIMATE.

Of the climate and seasons so little is at present known that, allowing all other difficulties to have been overcome, it would be very hazardous to risk flocks and herds beyond the head of the Murchison until the country has again been visited at a different period of the year, as it is probably that it has as yet only been seen under the most favourable conditions.

The fluctuations of the temperature are occasionally considerable; in the middle of June it some days amounted to 46 degrees in six hours--registering, at 7 a.m., 36 degrees, and at 1 p.m., 82 degrees; ice having been seen as far north as latitude 24 degrees 30 minutes.

The prevailing winds during the period of inundation appear to have been from the south-east, as most of the trees blown down while the soil was in a state of saturation lay with their tops to the north-west. In May and June the winds ranged between north-east and south-east.

Of the regularity of the return of the summer rains it is at present difficult to form a decided opinion; but, as far as observation would admit, I am inclined to think they cannot be relied on with any degree of certainty, to the southward of the 25th degree of latitude. The period at which they fall being about January and February, it is a significant fact that the grasses found buried beneath the mud during these months had generally attained only to nearly half their growth.

AREA OF AVAILABLE COUNTRY.

With regard to the quantity and distribution of the available lands, it will only be necessary to observe that, with the exception of 30,000 or 40,000 acres at the mouth of the Gascoyne, there is no land worth occupying for many years to come to the west of the Lyons River; the amount of land on this river has already been estimated at nearly 300 square miles, while on the Upper Gascoyne and its tributaries there is probably double that quantity; this, with the lands on the Murchison near Mount Hale, would make a total of about a million of acres.

A very important circumstance in connection with this district is the total absence, so far as we were able to observe, of any of the varieties of gastrolobium or euphorbia, which constitute the poisonous plants so fatal to cattle and sheep in other parts of the colony.

The means of access to the Upper Gascoyne and Lyons is another important matter for consideration. I am inclined to think that this district cannot be advantageously settled until the tract of country between it and the north coast has been explored, and a port established somewhere between Exmouth Gulf and Depuch Island, as, should the country in that direction fulfil its promise, the intervening space would very quickly be filled up, and the lands on the Gascoyne become available, its distance from the north coast being about 200 miles, while from Port Gregory or Champion Bay would not be less than from 340 to 360 miles--a difference of some moment in the transport of stores or produce.

From the lay of the country to the northward of the Lyons River there does not appear to be any reason to suppose that a river of any magnitude falls into Exmouth Gulf, as there would be hardly room for it between the sources of the Alma and the rivers flowing to the north coast.

I cannot bring my report to a conclusion without recording my acknowledgments to Mr. James Roe for the able and effective assistance he has rendered me throughout the expedition, the barometrical observations and management of the provision department having been especially under his charge.

My best thanks are also due to Mr. W.D. Moore and Mr. C. Nairn, who on every occasion endeavoured to relieve me as much as possible from some of the many arduous duties that usually devolve on the leader of an exploring party. Chainer Fairburn and the native Dugel also gave general satisfaction in the performance of their respective duties.

I may add that to the ready cooperation and unanimity that prevailed throughout the party may in no small degree be ascribed the successful issue of the undertaking.

I have the honour to be, Sir, etc.,

F.T. GREGORY,

Assistant Surveyor.

To the Honourable the Surveyor-General, etc.

***

NORTH-WEST COAST.

1861.