Breccia.--Pale ochre colour, silicious cement, extremely hard. Cellular, and sharp edges to the fractured pebbles. Has apparently undergone fusion. Occurs in the bed of the Darling in one place only. Sandstone Varieties.--Colour dull red and muddy white; appears like burnt bricks; light, easily frangible; adheres to the tongue; occurs in large masses in the bed of the Darling; probably in connection with the rock-salt of the neighbourhood, which, from the number of brine springs discovered feeding the river, must necessarily exist. Variety of the same description of rock. Jasper and Quartz.--Showing itself above the surface of a plain, from which D'Urban's group bore S. 40 E. distant 33 miles. It is a remarkable fact, that not a pebble or a stone was picked up during the progress of the expedition, on any one of the plains; and that after it again left Mount Harris for the Castlereagh, the only rock-formation discovered was a small Freestone tract near the Darling river. There was not a pebble of any kind either in the bed of the Castlereagh, or in the creeks falling into it. APPENDIX No. V. OFFICIAL REPORTS TO THE COLONIAL GOVERNMENT. * * * * * GOVERNMENT ORDER COLONIAL SECRETARY'S OFFICE, 23RD JANUARY, 1829. His Excellency the Governor has been pleased to order, that the following communication, dated the 25th of December last, from Captain Sturt, of the 39th Regiment, who is employed in an exploring expedition into the interior of the country, be published for general information. By his Excellency's Command, ALEXANDER M'LEAY. * * * * * WESTERN MARSHES, 25TH DECEMBER, 1828. SIR,--I do myself the honor to forward, for the Governor's perusal, a copy of my journal up to the date of my arrival at Mount Harris. I should not have directed the messenger to return so soon, had I not subsequently advanced to Mount Foster, and surveyed the country from that eminence. I could distinctly see Arbuthnot's Range to the eastward. From that point the horizon appeared to me unbroken, but the country to the northward and westward seemed to favour an attempt to penetrate into it. I did not observe any sheet of water, and the course of the Macquarie was lost in the woodlands below.