NATURE NOTES

New Zealand Herald, Volume LXXII, Issue 22100, 4 May 1935, Page 1 (Supplement)

NATURE NOTES

FIERY CLOUDS BY J. DRUMMOND, F.L.S., F.Z.B. A layer of fine sand, mingled with multitudinous particles or shreds of volcanic glass, at Arapuni, in tlio Waikato, may have been deposited from a spectacular volcano in the Tertiary Era, or later, according to Dr. P. Marshall. His theory is that the volcano sent up a fiery cloud,, which blazed fiercely, but cooled, rapidly on contact with the atmosphere and the ear ill. The sand and the glassy particles remain as evidence of the terriiic burst;. Dr. Marshall, who belongs to a band of geologists New Zealand is fortunate to possess, has written nothing more graphic than his description of immense clouds or showers of fragmentary molten material, heated in tense, y, represented to-day by rocks consisting largely of fine particles of glass. These rocks occur at intervals over an area of about 10,000 square miles, from Mercury Bay, on Coromandel Peninsula, to Tauranga, Lake Taupo, Tauiaarunui and the Waikato district. The glass, on the theory advanced, was hurled from liquid masses in the old volcanoes' burning fiery furnaces. At Arapuni, the particles cooled during transit to such a degree that tiey lost their stickiness, and did not adhere together after they fell. In other places, apparently, the glowing particles were so hot that they adhered all through the turmoil, even after they reached the ground. Dr. Marshall's experience is that the glass shreds, have retained their glassy characteristics in only a few places. In many samples ho examined the glassy nature has been lost, although the form of tie glass particles has been retained 01 is still visible in a maze of other structures. There is a great variety of these structures. They are so pronounced sometimes as at- first sight to conceal the structural features of glass shreds that disclose the origin of the far-flung rocks. They occur in places in massive outcrops. Thirty miles south of Arapuni there is an outcrop five hundred feet thick at least. Columns, resisting the action of the atmosphere,_ stand out conspicuously. At Arapuni there are columns one foot in diameter; at Ngutuwera, a few miles :south, three or four feet; atHinuera, north, of Arapuni, eight feet. The Hinuera type oj : columns reach a height of forty feet. For wide distances over the surface of ;he country the outcrops are obscured by heavy blankets of pumice. The pumice, evidently, represents a later phase of volcanic activity. It fell in showers on the surface of the rocks after ;hey were formed. The rocks do not seam to be definitely related to any volcanic cone, and no ' place can be .regarded as the point from which they arose in clouds of particles. This aspect of thu problem is left by Dr. Marshall at that. A suggestion may be made that some of the clouds were treated in the liame way as fine volcanio ash called tu:3: often is treated. Shot up to a great height, the ash is caught by the wind and is spread far and wide. The Tarawera eruption in 18S6 distributed tuff and lapilli, minute scoria fragments, over four thousand square miles. Quantities of the volcanic rocks whose history Dr/ Marshall, sketched were put into buildings in Auckland and Litchfield forty years ago. They show no .signs of deterioration. Supplies from outcrops have been used in railway \ works, especially in platform kerbings, in the lining of culverts, and in bridge approaches for fifty years. Here also no deterioration has been seen. The rocks are soft, but are distinctly tough. Embedded in their countless, shreds of glass there are crystals of felspar and quartz. Each of these substances, Dr. Marshall states, is immune from the' destructive effect cf weathering within an historical period, and there is no question as to the rocks' * lasting qualitias when to the atmosphere. In a quarry they break out easily. They are so soft that they can be readily squared without much expense. A secret revealed by the microscope is that volcanic rocks were molten glass when they were fired out. Some solidify as natural glass and look like artificial glass. This isi so with obsidian, sometimes called volcanic glass, black, brown or greanish, produced by the rapid cooling of an acid liquid mass in a volcano. Others retain only a small proportion of glass. Others have been converted into a stony state, all glass having disappeared from them. Pumico, scattered on the surface in many North Island districts, is frothed up by volcanoes. It J is solidified froth. Professor J. Park, of Dunedn, defines pumice as a light, frothy, fibrous, spongy glass that forms on the surface of acid lavan; it is the cinderv form of obsidian., and often it is composed of a matted mass of glassy fibres. Small pale blue butterflies recently were very plentiful in Westport. In sending a consignment, a. resident wrote: "I do not remember having seen them here until this summer. They are here everywhere. At the back of 'our house there is a Michaelmas daisy. They swarm on it in hundreds. In their movements they resemble tlin white butterfly. On the night of March 29, the coldest night we had had this summer, some remained on the plant all night. Early the following morning they were quite torpid. Members of the species seem to extract food from the daisy. Are they injurious to flowers or vegetables?" The species is one of the blues. A very good portrait of it i:a colours is in *Mr. G. V. Hudson's Butterflies and Moths of Now Zealand." It appears there as Lycaena labradus, occurring in great profusion at Kaeo, North Auckland, and in Nelson Prov- 1 ince, in lessc* numbers in many other parts of New Zealand, but it seems to be very rare in the extreme south. Mr. Hudson states, that it is on the wing from the beginning of October to the end of March, or in April. Like many other species of butterflies, it is widely distributed, taking in Australia, many South Pacific Islands, Timor, Celebes and India. An Australian butterfly book reports that this species, or a closely allied race, is tho commonest bluo in Australia. Its popular names there are common grass-blue, cloverblue, lucerne-blue, and bea.n-bluo. The caterpillars sometimes eat holes in bean pods, but Dr. G. A. Waterhouse, of Sydney, author of this book, dismisses tho damage in gardens as negligible. A strange phase 'in the life-history of another Australian blue butterfly has been written by Dr. Waterhouse. This is the fiery jewel; and no details of sparkling colours need be added to that title. The species is plentiful in parts of the Commonwealth, but has not been reported in New Zealand. A female usually lays her eggs at the base of a wattle. Small black ants cover the eggs with debris. As soon as caterpillars hatch from the eggs, ants attend them and carry them to tender young wattle shoots, on which the caterpillars fed. When the caterpillars can crawl to their food, ants guide them to young leaves. Having finished a meal they, are led back