118 



THE GEOLOGlS'r, 



40' of latitude, to at least the latitude of the sea mouth of the Murray. 

 Its strata are horizontal, and its surface generally quite level, or very 

 slightly undulated. Its greatest elevation may be stated at 400 feet 

 above the level of the sea. Its upper strata are beds of three or four 

 feet in thickness, composed entirely of common oysters and oyster-shells, 

 not broken or exhibiting marks of attrition. Below, there are much 

 deeper beds of mixed coral, echini, pectens, spirals, and other small 

 marine shells, generally much broken, and deposited in sand, limestone, 

 and sometimes selenite, alternating with beds of sand without shells. 

 At the base of these, or beneath them, are vestiges of fishes, teeth, and 

 nautili, of 4 or 5 inches in diameter. In the valley of the Murray, about 

 at. 35^ 6', are several points of granite projecting a few feet above the 

 surface of the flats : one of these, eight feet in diameter, forms an island 

 in the middle of the river. The neighbouring country, from its appear- 

 ance, is possibly the line of the highest elevation of the fossil formation. 

 Beds of the excellent compact limestone occur sometimes in the fossil 

 formation. The surface stratum is either a mixture, principally of sand 

 and carbonate of lime, the latter in a large proportion, or sand only. 

 The mixed sand or carbonate of lime is very extensive : immense plains 

 are wholly composed of it. On the banks of the Murray, from Lake 

 Alexandria to the Great Bend^, the surface of the fossil formation is co- 

 vered with a thick brush of slender trees, shrubs, and bushes. On the 

 north-western and northern limit of the great plains, there is exddently a 

 great drainage to the E. by N. or N. N. E. It is not unreasonable to 

 speculate, that this may, by an inconsiderable bend, produce by Altera- 

 tion, springs to supply Lake Victoria. As regards the province of South 

 Australia, the valley of the Murray in its whole length, i. e. for about 

 200 miles, is a hollow cut through this great fossil formation to nearly 

 the depth of the level of the sea; so that the hills and cliffs of either 

 bank stand sometimes close to the margin of the river, sometimes at a 

 distance of one or two miles from it, at elevations of about 300 feet. 

 The long lines of hills and cliffs which bound the Murray valley, main- 

 tain throughout a rougli parallelism to each other ; but the river scarcely 

 ever preserves an equal course between them. It sweeps continually in 

 magnificent reaches from side to side, forming perpendicular cliffs 

 wherever it strikes the hills, and encircling never-ceasing flats of from 

 half a mile to four or five miles in length. The great Murray fossil 

 formation is this province ; is bounded to the westward by the great 

 dividing range, which, commencing from the southward at Currency 

 Creek, Encounter Bay, Yankalilla, and Mount Terrible, unites into a 

 general ri(]ge to the north-eastward of Willunga, passes by Mount 



