EXPLANATION OP THE MAPS. 
31 
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which on the Northern Island, where crystalline (metamorphie) 
slate rocks have not yet been discovered, appears to be the 
oldest formation, the geological age of which it is impossible to 
state with exactitude, as petrifactions have not yet been discov¬ 
ered. The gold quartz veins which are to be found in the 
peninsula of Cape Colville (Coromandel harbour), are imbed¬ 
ded in this old clay slate formation. Frequent outbursts and 
layers of dioritie rocks correspond to the Silurian age. 
Distribution .—Upon the peninsula of Cape Colville, where it 
is covered to a great extent with recent volcanic conglomerate, 
containing rich gold quartz veins, which have given rise to 
mining enterprise since 1862 (Coromandel Gold Fields). The 
alluvial diggings arising from those veins are of little impor¬ 
tance. Upon the islands of the Hauraki Gulf, where the Great 
Barrier and Kawau contain veins of copper ore (copper 
pyrites, black and some red copper ore). Upon Waiheki are 
immense strata of jaspar and petrosilex; as also in the moun¬ 
tain chains of the west side of the Firth of the Thames, and 
thence in a southerly direction into the chains of Taupiri and 
Kakarimata. Further on they are covered by tertiary and 
volcanic strata, and penetrate to the surface only in a few 
localities. The mountain chains which extend from the AV el- 
lington district to the Taupo Lake and the East Coast, consist 
most likely also of old palaeozoic rocks. 
MESOZOIC (SECONDARY) FORMATION. 
The Mesozoic formation has been ascertained by the discovery 
of Ammonites and Belemnites in the entrance to the Waikato 
river, and in the harbour of Kawhia, although the exact age ot 
these strata cannot be fixed by the discovery of petrifactions up 
to this time, and which are enumerated as tollows :— 
1. A very large complex stratum of very regular and highly 
inclined beds of marl and sandstone, on the Waikato South 
Head, with 
Belemnites Aucklandicus (v. Hauer), 
Aueella plicata (Zittel), 
Placunopsis striatula (Zittel), 
Terebratula spec. ; 
At the Kawhia Harbour, with 
Belemnites Aucklandicus (var. minor), 
E 
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