PROBLEMS IN GEOLOGY

Taranaki Daily News, 20 February 1935, Page 4

PROBLEMS IN GEOLOGY

REVELATIONS BY EROSION CLIFF FACE AT NEW PLYMOUTH. VOLCANIC SUBSTRATUM EXPOSED. ANCIENT EARTHQUAKE UPHEAVAL? Erosion of the 50-feet earth, rubble and rock cliff-face at Woolcombe Terrace, New Plymouth, has presented knotty engineering problems to the borough authorities, who will have to undertake protective work sooner or later; but a geologist might be inclined to say it was almost worth while for the interesting things the gradual wearing away of the surface strata has revealed. Some time ago constant falls of earth and rock from the cliff-face west of Eliot Street showed the presence of a large tree buried in earth and sub-soil to a depth of more than 30 feet. Further falls have revealed the peculiarity of the occurrence of vegetable remains at such a depth. The tree is now shown to be lying on a solid substratum of sandstone which forms the base of the cliffs. Curving up and over its massive trunk is a layer—on the bottom of the band of sub-soil—of material which bears a close resemblance to volcanic rubble, ash and coarse volcanic conglomerate. ’ Vegetable remains occur repeatedly in this layer and for some considerable distance one may observe the semi-fossilised remains of small branches protruding from the exposed section of the stratum.

The problem for the geologist to determine is whether the tree lies on the bed of some long since dry stream, the ash and conglomerate having been deposited by running water over its trunk, or whether it has been “swamped” more sensationally with volcanic material from some eruption of Mount Egmont or cataclysmic earthquake upheaval thousands of years ago. The mere fact that 30 feet of hard packed clay conglomerate and soil overtop it is definite evidence that the time hardened remains of the giant, at present being gradually dug out of its tomb by the action of frost,’ wind and water, have lain deep in the earth for a time that is almost beyond human imagining.

Still, geologically speaking, things happen quickly on the quickly eroding west coast of the North Island. The Woolcombe Terrace erosion, according to recent survey figures, has advanced 26 feet since 1929. Earthquake faults have made the district one of the most geologically difficult in the southern hemisphere. Within living memory sheep and cattle, used to graze on the now bare, tide-washed point of rock that projects into the sea just east of East End beach. Almost constant falls of earth and rock from the Woolcombe Terrace cliffs make a close examination of the face a rather risky business, and borough officers have warned children of the danger of walking on the beach and rocks too close to the cliff itself.