NATURE NOTES

New Zealand Herald, Volume LXXI, Issue 21972, 1 December 1934, Page 1 (Supplement)

NATURE NOTES

MEMORIALS TO TOILERS

BY J. DRUMMOND, i'.L.S., F.Z.S

Hard, pure and crystalline limestone, standing like castle walls, in parts fifty feet high, on the shore of Raglan Harbour, induce Mr. P. L. Hill, a resident of the district, to think of the little marine creatures whoso remains built up the massive rock. He says he is surprised at the level positions of the layers. They have no tilt except where they have been undermined and have toppled into the harbour. They rest now as when they were formed on the bottom of the sea. They contrast with formations of other rocks at the head of the harbour, ten miles away. These have been broken in huge blocks and tilted at all angles. The surface there is a jumble. To Mr. Hill's mind, rocks that lio in a kowhai grove, which tuis, bellbirds and grey warblers find pleasant places, are memorials in a fitting setting to the limestone-makers, who lived millenniums ago.

Limestone laid down in the Tertiary Era, which immediately preceded the present era, a few miles north of North Head, Raglan Harbour, is very rich in fossils. Rocks there are full of the remains of big oysters and of scallopshells and lamp-shells. The fossil tooth of an extinct species of shark, once very plentiful in New Zealand waters, was found at Raglan. Worms that burrowed into soft sediment died and disappeared, but some of their trails are preserved in cliffs on the harbour shore. Things like this may seem trivial. Geologists regard them with interest, and accept them as reliable evidence of the conditions under which the sediments were laid down. Burrows made by worms, and the trails of worms, are among the oldest fossils known. In other countries, the trails are found in rocks of the Cambrian system, the oldest rock of the era of Early Life.

Most of the limestone in the Raglan district seems to have been made by foraminifera, like the stars for multitude, very minute in size, but giving to the world some of the largest and most important limestone deposits. They played an important part in making chalk in the Cretaceous Period. Foraminifera still carry on. They are conservatives. The type unlike, types of higher creatures, has neither advanced nor been modified in any material respect since the days of Early Life. Members of one group of them are particularly abundant in the Atlantic Ocean. They are part -of the microscopical floating population near the surface called plankton. After they die their dead shells, chambered, horny, limy, exquisite, sometimes patterned in elaborate designs, fall in hundreds of thousands on to the ocean's floor, to make a grey ooze that may become solid limestone rock.

In several respects the neighbouring ' districts are attractive to geologists. Dr. J. Henderson and Mr. L. I. Grange, in a geological report, mention peculiar holes near Ngarnawahia and Taupiri. They are round or oval, and funnelshaped, about one chain wide and twelve feet deep. In most cases their lips are flush with the surface of th(T ground. Their sides usually are covered with grass and slope from the lips to the bottom. Below the lips in some there are miniature precipices, three or four feet high, composed of pumicesand. Most of the holes are scattered haphazard over flats. In places, three, four or even seven holes are in lines. There are a few holes between Cambridge and Horotiu. From there they increase in number toward Ngaruawahia. Away from the Waikato River holes are rare. A theory is offered that the holes were made by sub-surface streams that drew loose material away from the surface.

Further south there are many underground streams and sinkholes. Dr. Henderson and Mr. M. Ongley say they believe that neax Waitomo, probably, there are miles of subterraneous passages. Sinkholes, plentiful in limestone country, there are important features of the landscape. In some areas that cover several square miles there are no running streams, and the only surface water in fine weather is found in the swampy bottoms of the sinkholes with which the surface is pitted. All the surface drainage goes through them to underground streams, whose courses are marked by series of sinkholes. The Waitomo River flows through the lower gallery of the Waitomo cave for a few chains. Many branches of the Mokau and of other rivers have subterranean courses. The head waters of the Mangapu River flow underground for two miles.

For seventy years persistent efforts have been made to introduce the common European lobster into New Zealand. The first effort was by Mr. A. M. Johnson. He had an aquarium and fishponds at Opawa, Christchurcli, where he made many important experiments in acclimatisation. When on a visit to Britain in 1864 he obtained twentysix lobsters in Wales. He kept them in a tank on the vessel. Full of fight, they carried it to a finish until only one was left alive. Mr. Johnson sold it to a first-class passenger. Twelve lobsters taken on board a vessel in England by Mr. S. C. Farr for the North Canterbury Acclimatisation Society could not stand the heat of the tropics and died. The first lobsters landed in New Zealand were shipped to Dunedin forty-one years ago. There were nine of them. Alt were liberated at the entrance to Otago Harbour. They were not heard of again. From 1906 to 1908 fortyseven lobsters arrived at the Portobello Marine Fish Hatchery. Twenty-four wore females. As usual with lobsters, they laid innumerable eggs. In 1908 36,000 young lobsters were hatched ir. the tanks, and in 190!) 100,000, and young lobsters were liberated in the sea near Otago Harbour. Tn 1913 another consignment of adults, fourteen males and twenty-eight females, arrived from England.

A moderate estimate by the late Hon. G. M. Thomson, who entered heart and soul into the work at tho hatchery, placed tho number of lobster fry liberated from Otago Harbour during the first fifteen years of the attempts at more than 1,000,000. He knew that the young lobsters would live mainly concealed among rocks and seaweed, and that they probably would not be caught, but ho always hoped to learn that some had been seen near the coast, a hope that was not gratified " We are still trying to rear lobster fry in our tanks to a stage when they can deal with their enemies," Professor W. B. Benham wrote from Dunedin on November 10 last. " In 1931 we liberated 200,000 youngsters in the sea, but they were in such an early stage of development that they, doubtless, fell an easy prey to fishes and other enemies. As to results, I grieve to state that up to the present no undoubted lobster has beon caught or seen in our seas. We are still trying to rear them to a stage when, we hope, they will be sufficiently strong or active to deal with all inimical conditions of life. In spite of a reduced Government grant, we keep the station in good order, but until our former grant is reinstated we are merely marking time.