IN TOUCH WITH NATURE

Otago Witness, Issue 3673, 5 August 1924, Page 6

IN TOUCH WITH NATURE

A CLASSICAL MORAINE.

(By

J. Drummond, F.L.S., F.Z.S.

Battlers in the Waihola district-, Otago, in the early seventies, used for road metal and house foundations some boulders that formed part of a vast classical moraine, transported and deposited by, probably, Pleistocene glaciers in New Zealand’s Glacial Period. The boulders rested near a road level between Waihola and Otokaia. One mass, which .'ay on a flat at the foot of a slope half-way between Manuka Gully and Taieri Bridge, produced about 160 tons of road metal. On ridges between Titree and Otokaia there still rest many transported buolders from live tons to fifty tons in weight: an exceptionally large one weighs about COO tons. The boulders, apparently, were transported by the glaciers fiom mountains on the west side of the Taieri Plain. Professor J Park, making his headquarters at Henley, has made a particular study of that great moraine. He found that slopes of ridges that front the main road, and slopes that descend to Manuka Gully, are occupied completely by slipped morainic ground. The slips, in many places, extend from the summit of the ridge to the level of the plain, a vertical height of 400 ft. Following to their source many angular blocks of mica schist, Professor Park found that they had come from close to the summit of the ridge. Between Waihola and Otokaia, the Taieri moraine forms hills from 250 ft to 700 ft high. The lower division of the moraine consists of a succession of red clays, gritty and sandy clays, and beds of water-worn gravel, which usually contains a largo proportion of small angular fragments of micaschist. The moraine, in places, has a thickness of 1500 ft, and it may be traced for

a length of about- twenty-two miles and a widtn of from one mile- to three miles. It reaches its northern limit at- Saddle Hill, but small areas of glacial till—stiff clay formation, or boulder-clav—occur in the Kaikorai Valley, particularly at Fernhill coal mine, Abbotsford, and Burnside. Professor Park states that the moraine at Abbotsford is a typical example of glacial till- That material consists of peaty clays contain moa bones, usually much decomposed, yellowish-brown clays that contain bouldery gravel, and clays with a confused mass of boulders. On the evidence collected. Professor Park expresses a_ strong opinion that that immense glacier was a continuous ice-sheet, not a series of valley-glaciers. It descended from a distant mountain divide in Western Otago to the present coast line, occupying tire Taieri and Tokomairiro Basins, from Dunedin to the Clutha, and representing a continuous ice-face more than 40 miles long. Debris left in its track is evidence that it strode over the coastal range on its way to the sea, “From Moeraki to Oamaru, and north to Timaru,” Professor Park writes, “the surface of the land everywhere bears the impress of erosion by ice. Nobody can view the landscape with its beautiful smooth contours and domed and truncated crests without being impressed with the small part erosion by rivers and streams has played in modifying the ice-worn surfaces of New Zealand’s Glacial Period.’’ It is 48 years since Mr J. T. Thomson, chief surveyor of Otago, and later Sur-veyor-General of New Zealand, first published the theory that Otago had been covered by a continuous ice-sheet. His theory has been criticised by some New Zealand geologists, one of whom has inferred that hq was hot-headed. Professor Park, who has developed tho theory and supported it by evidence he has collected

for many years, describes Mr Thomson as “a competent geographer and a distinguished mathematician.” The theory may have been suggested to him by evidence of ancient glaciation in Scotland, and the work of valley glaciers in the Himalayas, seen by him before he came to New Zealand. There seems to be an agreement amongst those who speak with authority that tire great glaciation of New Zealand was caused by a general elevation of the land. It was 3000 ft, or more. It flung out the boundaries of this country hundreds of miles east and south, the southern boundary reaching within about 700 miles of the Antarctic Continent. There is some difference of opinion as to time of the great glaciers, but all students place them sometime in the Tertiary Era, which immediately preceded the Recent Period. 'Two epochs of the glaciers are distinguished by Professor Park. To the older epoch he ascribes the glacial deposits at Blue Spur, Taieri, and Kaikorai, in Otago, and the great bouldei till in the Rangitikei Valley, Wellington; to the later epoch he ascribes valley moraines, glacial dams, and drifts in the South Island. In the first epoch, according to his conclusion, there was widespread glaciation; in the second epoch, there were immense valley glaciers, which made minor advances and retreats before their final recession to the glaciers’ alpine strongholds. Evidence that, in former geological times, there was land connection between New Zealand and South America is supplied bv plants and animals now found in both countries. _ Amongst the plants the evidence of the yellow kowhai is particularly valuable. The latest zoological evidence is supplied by a lowly isopod. a member of the order of tho crustaceans. There arc many species of isopods ; most of them are

small, many live in the sea, others live in fresh water, others, including the pillbugs, live on land This isopod, Ligia NovaeZealandisc, which is another link between the two countries, now far apart, was discovered on the shores of the Bay of Islands by the United States exploring expedition under Wilkes about 85 years ago. Another isopod collected at Valparaiso was named Ligia cursor. Two years ago an opinion was expresed that these isopods belonged to the same species. Dr C. Chilton, rector of Canterbury College, who made an extensive study of New Zealand crustaceans, recently received from the Buenos ■ ires Museum a female of the Valparaiso isopod, labelled “Ligia cursor.” He is unable to distinguish this female from females of Ligia Novaa-Zealandiee found on the New Zealand coast. If the two species are identical, the title bearing the name of this dominion, on the laws of zoological nomenclature, must be retained, and South American specimens as well as New Zealand specimens must bear it. "Shore isopods and land isopods,” Dr ’hilton states, “carry their egg s in ’ broad pouches under their body, until the young are hatched in a form almost the same as an adult, and it is very unlikely that they could cross large tracts of ocean. Th o presence of the isopod in New Zealand and outh America—it occurs also in Juan Fernandez —is additional evidence of former land connection between those places. A shore amphipod, which lives under exactly (lie same conditions as Ligia Novie-Zea-landise, is found on the shores of Now Zealand, Chile, and Juan Fernandez. Mrs V. E. Calvert, Hillsborough, New Plymouth, reports that she found the cup orchid, Petalochilus calyciformis, amongst scrub at Strathmore, about 20 miles in from Stratford. It is about five years since she visited that place, but she states that

if the scrub ha s not been cleared individuals of the species probably grow there still. The cup orchid described in this column in May list is one of the latest additions to New Zealand’s list of the orchids. It has attracted the attention of botanists in the Old Country, and it was given a prominent place in one issue of tho “Journal of Botany,” published in London, early this year. Mr H. B. Matthews was its discoverer. Previously it was reported from only the Mangonui County, North Auckland. Mrs Calvert’s note shows that this splendid plant, ornamented svith a tiny cup, may be more plentiful than was believed. The fear that it will not be available to students of New Zealand’s flora seems to bo groundless. This, in view of the regrettable scarcity of some species of New Zealand birds, the rareness of New Zealand’s two frogs, the decrease of tho Maori rat, and the extinction of the Maori dog, is very satisfactory.