EXPEDITION TO FIORDLAND

Press, Volume LXXXIX, Issue 27065, 13 June 1953, Page 9

EXPEDITION TO FIORDLAND

Mystery of New Zealand’s Glacial Period ANSWER SOUGHT BY GEOLOGISTS AND BOTANISTS [Specially written for “The Press” by W. B. STEWART) On October 27, 1862, two men stood on thehighest peek at toe south-west end of the Takitimu range, south-west Otago, and looked across country to the two lakes, Monowai and Hauroko. They were probably the first white men to see them. That brief glimpse had cost the men weeks of through rugged, bush-covered, often virgin country, it had cost another man his life, drowned while helping them to cross a flooded river. Since J. McKerrow and J. Goldie first saw .Monowai, many tors, deer cullers and trampers have entered the area, tattle scientific work has been done, however, and recently a party of staff members and students from the science faculty of the University to Monowai to begin a study of the region. worked from both ends of the L-shaped Lake Monowai back to Mount Burns, roughly a day and a half’s tramp from their base camp. ,

A study of toe general topography of the area in order to find the probable routes of the original glaciers was made by Miss E. L. Elliott. A huge basin in front of Mount Burns seems to have been an amphitheatre of ice feeding into a glacier which skirted round the 5000-odd feet Mount Cleughearn, and then eroded the hollow in which Monowai now lies. In the northern hemisphere it is thought that there were four Ice Ages the first occurring (very roughly) 500,000 years ago; the last ending about 10,000 years ago. One method of estimating these figures was first made possible when a lake in Sweden was emptied. It was then found that seasonal thawing had deposited alternate lavers of heavy and light silt on the lake floor. By counting the number of such layers, the age of the lake was determined. Research in New Zealand, however, has not been able to reveal definite evidence of more than two Ice Ages, and the story of

the glacial period in this country remains much of a mystery. . While Miss Elliott was. studying these geographical features, formed 10,000-plus years ago, geologists were mainly investigating the roclj: formations of this so-called plex which dates back some 200,000,000 years. Parties on the tops coliectea specimens, while Dr. D. S. Coombs and Mr D. Hamilton studied the good rock exposures round the lake shore. “A fault in the earth’s surface helps to define the limits of Fiordland,” said Dr. Coombs. “The Waiau river basm to the east of the fault has at some time sunk relative to the Fiordland block and is now occupied by sedi- ■ mentary rocks of the tertiary period—--1 that is, rocks deposited in toe last ! 50,000,000 to 60,000,000 years.”

One Major Discovery i Little was known of toe Fiordland I Complex in the Monowai area. How- , ever, it now appears that toe complex : is here similar. to toe area round » Manapouri, 25 miles to the north. In t both areas igneous rocks (that is, t jocks formed from moxten material) - have invaded the ancient, recrystalr lised sedimentary rocks, perhaps J some 200,000,000 or more years ago. b At least one major discovery of very 1 great interest to geologists was the • finding of a large intrusion of a rare - rock type. This “peralkali granite’ is : entirely new for New Zealand and f quite unexpected in Fiordland. By 1 coincidence, Dr. Coombs had madfe a • trip to Ascension’ Island m the South • Atlantic to study similar rocks Which ‘ occur there as small fragments DiTA-um nut hv the island’s volcanoes.

thrown out by tne isiana s volcanoes. The collection of specimens in the field is but the beginning of the scientific work. Constituent minerals in the rocks are chemically tested, crystals are sometimes photographed by means of X-rays, and an inspection is made under the microscope. For the latter, sections of rock have to be ground down to transparency, about 0.03 millimetres. Seen under polarised light, these thin transparent “slices” present a variety of reds, greens, blues and other colours which help identify the constituent minerals, their structure and inter-relationships. “The full interpretation of crystalline rocks such as those found in Fiordland depends on these investigations, ’ said Dr. Coombs, “and the data already collected must’ be systematised before we return to the area.” Botanists in the part were mainly

classifying the plant life of toe region. A search for Ranunculi was one aspect of this activity. Mr F. Fisher, who is making an over-all study of the range and variation of Ranunculi throughout New Zealand, tells something of toe fascinating story behind this search. Ranunculi—which range from the common, introduced buttercup to the lovely Mount Cook “lily* (Ranunculi lyallii)—are of two main types. These are the lowland, which are found up to 4000 feet, and the rilpine, found from 4000 to 9000 feet, each type containing about 25 species. Of the alpine species, four main groups can be distinguished—the snow, the cliff, the scrub and the swamp. In fact, the plants vary even from one mountain range to another in such characteristics as the degree of division in their leaves and in the hairiness. The particular Ranunculus sought in Fiordland is one of the scrub group, with finely divided, smooth leaves. This group, however, shows considerable variation, and Mr Fisher wanted to find a “missing link” which would enable him definitely to link the Variations. A single specimen which provided a clue had been collected by Professor Arnold Wall on Mount Cleughearn in i 1926. The re-finding of a large population on this last trip provides that missing link. This also fills in more details in the general picture of the scrub and cliff j Ranunculi throughout the South [ Island. It appears that the scrub type t originated in Otago and has slowly t spread up the island as far as Canl terbury, while the cliff type, probably . beginning in Marlborough, has spread . southwards to Geraldine.

This leaves a patch where the two groups overlap, and by studying this patch it is possible to find out something of the evolutionary history of the plant Interbreeding of Plants As with the geologists, the collection of specimens in the field is often the beginning of the botanists’ work. For instance, one criterion used to determine the relationship between plants is the relative ease with which they interbreed. •An important factor here is the number of chromosomes or microscopic particules in the ptant cells. Two specimens usually interbreed successfully only if the number of chromosomes are the same in both. Thus, one method of relating the species is to count the number of chromosomes in each. This involves microscopic enlargement up to 3000 times and if the specimen contains numerous chromosomes the job may be diflacult. Often Mr Fisher has to grow Ranunculi under conditions similar to which they are found. To this end he has designed and built a pair of controlled environment cabinets in which, by the regulation of temperature and humidity, he can simulrfte a wide range of climatic conditions—“without too much exaggeration, from , desert conditions to alpine.” These then, are some of the activities of the group of scientists who went to Monowai. The trip, which was financed partly by the Otago University Students’ Association and partly by the party members themselves. was successful enough to war- ! rant the hope that, when their present data have been studied, more visits r will be made to the area.