GEOLOGICAL SURVEY.

New Zealand Herald, Volume LX, Issue 18471, 7 August 1923, Page 8

GEOLOGICAL SURVEY.

NORTH AUCKLAND AREAS/

, ECONOMIC 5 RESOURCES.

NO INDICATIONS OF OIL.

(by TELEGRAPH.—SPECIAL . REPORTER.] ..;,:'.' '"/ WELLINGTON. Monday.

The- annual report of the ;■; geological survey/ branch of the Mines Department was presented in the House of Representatives ; to-day. ; , , .

Field; work during the; 1922-23 season covered the southern part of the Dargaville ; subdivision, which, >in the main, is a ,strip of ; country J extending across the North Aucklan/1 peninsula from the coast south-west of Dargaville to Bream Tail. The adjoining peninsula north of the entrance to Kaipara Harbour was also surveyed. : ,', :.-,.•...■ .'/;.;.,"■ ;>: ;--v _

Attention was given to the soils, the limestones (which cover large areas, and are of great value), sands, clays, and kauri resin deposits. Coal occurs hear Waipu, but there is little likelihood -of any workable seam being present. Outcrops of volcanic and other rocks suitable for road-making were mapped wherever they occur, and the Information obtained will be of value to road engineers and others. v ' The report of Mr. H.T. Ferrar on the Dargavilfe subdivision states that deposits of high-grade limestone, of use to agriculturists, .; have been delineated, and large arias, which are covered ?by argillaceous limestone, similar to the hydraulic limestone .; used at ? Wilson's ; (New Zealand) Portland cement works, have been surveyed. ■' Outcrops of igneous rocks, suitable for macadamizing. roads, have ■ been carefully mapped. Such rocks' occur 'in quantity in some localities,:[ but are absent from others. A studv of the geological maps, when published, will show which outcrops are easiest of access to such localities as require road metal. Silica sands, suitable for glassmaking, abound in some localities, but ceramic clays are scarce, The kauri resin deposits, as is shown by their distribution, accumulated under peculiar conditions, and .mapping Will:. enable the State to utilise for settlement such resin-tree land, which is at present held in reserve. deferring to supposed petroleum indications near Silverdale, Mr. Ferrar says in the Silverdale (Wade) district comparatively undisturbed sandstones belonging to the Waitemata series unconfonnably overlie, claystone and argillaceous limestones, probably : belonging to the Onerahi formation of North Auckland. The latter are underlain by serpentine which in places formed the sea floor upon which the Onerahi beds were deposited. • In • Matthew's : quarry (section 29, block 11, Waiwera Survey District) boulders of serpentine occurring one foot above a smooth : surface of the same rock show that it does not intrude the argillaceous limestone. A note is inserted as follow.'!:— sor W. N. Benson has stated that he has been informed by Mr. J. A. Bartrum that the serpentine at Wade has been injected into the hydraulic limestone. This statement, if. correct, would not only invalidate that made above, but would justify far-reaching deductions, one of which is suggested by Professor Benson. In one locality an epidioritei probably an altered gabbro, - associated with the serpentine, underlies the Waitemata beds. McKay and Park, who examined the Silverdale or Wade district many years ago. made no mention of oil indications, and the driller who put down the borehole in 1910 affirms that he saw no indications of oil. The borehole and two coal prospecting shafts sunk on Oak Farm (Carter's) penetrate disturbed argillaceous limestone beds which apparently belong to the Onerahi formation in North Auckland. No indications of oil and no beds capable of forming oil reservoirs-, have yet been found associated with this formation. In the present case there were no indications of oil whatsoever.