120 
Mines and Mineral Statistics. 
The Pleistoceuc drifts exceed in importance those of the recent, 
being of far greater extent, and equally rich in alluvial gold and 
tin. In the diggings districts they are seldom more than thirty 
feet thick. Mr. Chas. de Poos, Warden of the Grold Fields, 
Southern District, iu his report on the Araluen Valley, where the 
stripping is from twenty to thirty feet, says : — “ To give an idea 
of the work carried on, I may mention that one claim — that of 
Herbert and party — employs at the present time seventy men and 
forty-five horses, whilst they have three powerful engines on the 
ground. Only two other extensive claims are at \vork. and these 
em])loy somewhere about fifty men each and thirty-five horses, 
besides the engines and machiuery for pumping.” 
In Xew Eiighiiid the drifts contain rich stores of stream tin, 
and are now extensively mined. They will continue to afford 
profitahle employment for many years, after the more easily 
worked recent drifts have been exhausted, 
Pltocese. 
Most of the present surface features have had their origin 
during the Pliocene period. The Eeceiit accumulations are those 
no'sv in process of formation ; and we have seen that the Pleisto- 
cene drifts, &c., include those wliich were deposited whilst the 
present valleys were being eroded ; and, in pursuing our investi- 
gations further, we observe that the formation through which 
mxny of tliese valleys liave been excavated is basaltic traj), and 
that this volcanic rock in its molten state has filled in and covered 
up older river courses, whicli existed and Imd their origin in the 
Pliocene period. W^e again further notice that these older 
valleys Iiave cut through thick strata of gravels aud clays, 'which 
bail been deposited siuce the Miocene period. Between the 
Pleistocene and Miocene epochs, we have thus, at least, two dis- 
tinct series of deposits, which may be classed as Upper and Lower 
Pliocene ; the former embracing those old fluviatile drifts buried 
hi places beneath basaltic lava ; the latter, those wide-spread 
auriferous gravels and clays which appear to be of marine origin. 
Our geological history, therefore, reveals this important fact, — that 
after the IStiocene period, this continent was submerged beneath 
the sea, when the Ijower Pliocene marine deposits ivere formed ; 
and again raised and subjected to rain and other atmospheric 
denuding agencies, whoso well-known influence gave rise to that 
general system of valleys which now furrow the slopes of the 
Cordillera. There is no evidence to show that the land has been 
again submerged siuce the Lower Pliocene times ; on the contrary, 
the present physical features rather indicate that the atmospheric 
denudation which then commenced has continued to the present 
day, disturbed only by several volcanic emissions, which chiefly 
at the close of the Pliocene epoch occurred. About this time, 
