94 
resulting inequalities of the surface to be planed smooth, leaving 
no trace of the faults at surface. The sunken field at Coolgardie 
for instance looks just the same at surface as any of the shallow 
flats in its vicinity. 
It seems probable that the movements of elevation and sub- 
sidence of this country have been mainly epeirogenic rather than 
erogenic ever since Palaeozoic times. The Nullagine scries of 
beds are usually characterised by gentle undulatory bending without 
severe folding; the Carboniferous beds mostly lie at low angles of 
dip without much appearance of bending, and the strata of Meso- 
zoic and Tertiary age seem usually only very slightly tilted from 
their original bedding. Since the time when the Nullagine beds 
were subjected to a certain amount of orogenic crumpling there 
appears to be very little if any evidence that any of the 
subsequently formed strata have been compressed into undulatory 
folds to any ai>preciab1e extent. At Collie the tilting of the beds 
of the coal measures seems princi])ally due to faulting rather than 
crumpling. In epeirogenic movements of elevation, faulting in 
parts of the moving landmass must be expected as a natural conse- 
quence of the readjustments of ])ositiou of material incidental to 
the movement. An elevation or subsidence of an area of la!id of 
continental dimensions like the Western Australian Plateau would 
also require us to assume the existence of powerful faults forming 
the boundaries of the moving block, and it may be noted that the 
probable existence of some such faults has already been deduced 
from entirely dilTerenl considerations, along l)oth the southern and 
western coasts of this State. There is too little evidence to enable 
one to say yet whether there is any indication of the last elevatory 
movement being merely an even vertical one or vN'hcther one or 
other side of the block has been upheaved more than the others. 
It seems possible that the physiographical evidence may yet be 
so systematised as to lead to some positive conclusions being drawn 
on this point. A little tilting of one side or another of the moving- 
block of ground obviously might have very important effects in 
modifving or even reversing the directions of slope of various 
parts of the surface, and so altering the flow of surface waters. 
I'he most positive indications of marine conditions in the 
interior of our State are those already mentioned as having been 
found in the Norseman district near f^ake Cowan. Here there are 
two occurrences of remains of undoubtedly marine organisms, one 
a thick l)ed composed almost entirely of sponge spicules, described 
by Hr. Ilinde, in the Princes Royal Deep l^^ad, and the other a 
bed of marine shells in limestone, found by Mr. Campbell near the 
Norseman Causeway. The shcllbed is described as l)eing feet 
above the level of Lake Cowan, and containing opalised casts of 
several s])ecies of late Tertiary or recent marine shells belonging 
to the genera. Tiirritclla, Pcctcn, Carduim, and Magcllania. The 
