214 Influence of the Physical Character 



property of carrying what water it does absorb directly 

 downwards ; Avhen it reaches the next formation, which, in 

 this country, is most often inclined clay slate, it will 

 penetrate to great depths, and ultimately reach the sea, at 

 much lower levels than the river basins, because, when the 

 clay-slate rocks are secured from the action of the weather, 

 they are decidedly permeable. 



To show how water is retained on the surface of basaltic 

 rocks, permit me to direct your attention to section No. 4, 

 which is draAvn across the basaltic hills near Melbourne. The 

 hollow shown in the section is a swamp in winter, receiving 

 the drainage water of the adjacent hills, where there are thin 

 tertiary beds. The trend of the land is toward the Saltwater 

 River, but there is no true water course. The owner of the 

 land has sunk a pit about four feet in depth, and he has 

 obtained a small supply of water during this summer. It is 

 by no means of good quality. This section shows the usual 

 manner in which swamps occur on basaltic flats. 



In thus treating generally of the geological formations of 

 this country I have omitted a description of merely excep- 

 tional cases, such as craterlform hills, &c., &c. My object 

 has been to shew that the thin tertiary beds are the principal 

 reservoirs in this country. And according to the elevation 

 of the land, and the prevalence of schistose rocks, so are 

 these numerous and moi'e extensive. 



Now instead of thirty feet of tertiary gravel and sand 

 resting on paleozoic rocks, let us suppose a basin to exist in 

 the district of Mount Alexander, somewhat similar to that 

 shown in section No. 5. The granite in this instance is 

 covered with a vast thickness of sandstones, shales, and beds 

 of coal. The dip and arrangement of the strata are favour- 

 able to the absorption and retention of water. The beds are 

 disturbed by fardts, which permit the water to descend with 

 rapidity, as the fissures thus created are filled with sand or 

 sandy clay. The rain, instead of falling on steep and naked 

 ranges, whence it rapidly flows to the river basins, is received 

 on well bosomed hills, and in gently sloping valleys. The 

 alluvium of these valleys, like that resting on the clay slate 

 rocks, becomes saturated, and the water, percolating through 

 to the sandstone beds, is thence conveyed through innumer- 

 able fissures and faults till it meets with an impermeable bed 

 of clay. 



In strata, such as is shown in the section, it is not unusual 

 to meet with two or more distinct sheets of water. At the 

 edge of the granite^it will be seen several beds are basseting 



