AUCKLAND SCENERY

New Zealand Herald, Volume LXXII, Issue 22191, 19 August 1935, Page 10

AUCKLAND SCENERY

GEOLOGICAL ORIGIN EFFECTS OF EARTH MOVEMENTS The interesting relation between earth movements and tho scenery of the Auckland district was dealt with yesterday afternoon by Mr. C. W. Firth, M.Sc., in the course of the sixth Sunday lecture of the season arranged by the Auckland War Memorial Museum. The lecture was very well attended, in spite of the weather. Mr C. It. Ford acted as chairman. s Great block faults, stated Mr. Firth, had been responsible for the deep depression of the Firth of Thames and the Hauraki Plains. The Hunua Ranges, the Clevedon Hills, and tho sharp cliffs that bounded the Manukau to the north had all been caused by faults of a major order, while the Waikato area was bordered by a scarpment of fauit origin round which the river was forced to deviate in order to reach the sea.

Generally the faults of the Auckland district ran more or Tess north and south, meeting the system that ran across the island in the Taupo district. This weakness in the earth's crust was responsible for the thermal activity at that area. Similar junctions made for disturbances in the Mnrchison and Wellington districts. Illustrating minor earth disturbances, Mr. Firth showed a number of fine lantern slides of tho cliffs bordering the Hauraki Gulf, the rocks of tho Waitemata series forming the shore line, affording many excellent examples of what normally wero hidden deep in the earth. Dealing with tho geological historv of the earth, Mr. Firth explained that there had been at least six rhythmic movements, each lasting many millions of years. In these, continents* had been elevated and oceans depressed. Contrary to general opinion, although land masses wero being steadily eroded, they were also becoming lighter, and so tended to float higher out of tho plastic layer below them, while the enormous weight of material being poured on to the sea floors still further depressed them. Thus it was that especially along the continental coasts, mountains were being steadily elevated and great ocean deeps were most likely to occur.