75 
“deep leads/' 
In writings on the subject of our plain country it has been 
somewhat usual to have a good deal of insistence jilaced upon the 
point that in them the bedrock is generally very close up to the sur- 
face so. that there is only a very small depth of soil covering it. 
7'here is no doubt that such a condition is of very common occur- 
rence, there being many places where the planed surface of the 
bedrock is practically bare. This is well seen in several places 
along the shores of Lakes Cowan and T.efroy, in the case of which 
it can hardly he attempted to be questioned that the levelling or 
planing agent has been water. Yet it is known from the few bor- 
ings which have been made in these lakes, that the detrital material 
in one case at least, is bTT feet deep below the present surlace of 
the lake bed, and so little has been done to test the depths of the 
basins that it is entirely i)rematurc to assume that they must always 
be shallow. It must be regarded as still quite an open question 
whether these lakes ought not to he regarded as filled iqi valleys of 
quite considerable depth rather than shallow eroded rock basins. 
There is quite a large (piantily of evidence now accunndated on the 
subject of the ’‘alluvial deep leatls" not uncommonly found on our 
goldfields, wliich goes to show that under the i)lains there often 
arc numerous valleys of considerable depth in the bedrock. Some 
examples mav be citexL^ — The "Lady Mary lead near Norseman 
is a buried watercourse running into the Lake 1 )uiidas basin. 
Where the lead was first found the ground was shallow, but as it 
was followed towards the lake the prosT)ecting shafts iKcame suc- 
cessively deeper, up to at least "0 or ^0 feet, the grade of the old 
watercourse falling more steet)ly towards the lake than that of the 
present surface does. If both grades continue as at present, the 
valley of the old watercourse must lie well over 100 feet below the 
level of the present bed of Lake Dundas. 
The “Princess Royal” lead is a quite similar buried water- 
course, running under the residence areas at Princess Ro\al and 
out towards Lake Cowan. The shafts down to the auriferous 
“wash” were shallow at the southern end. but the lead became 
deeper and deeper as it went towards the lake, and the last shafts 
were about 00 feet deep. It was in the workings from one of these 
shafts that the sponge spicule deposits described by Dr. Hinde wewe 
discovered, which he has taken to he of deep sea origin. The 
bottom of this lead below Lake Cowan is probably quite 100 feet be- 
low the present bottom of the lake. 
At Kalgoorlie there are several well-marked "deep leads” 
formed by a system of buried watercourses running from the Mari- 
tana Hill westerly and southerly under the flats on which are the 
towns of Kalgoorlie and Boulder. Near the hills the "leads” are 
shallow, but they attain depths of 00 to 100 feet below the flats. 
The surface slopes very gradually and gently to Hannan’s Lake, but 
