GLACIERS AND GOLD.

Cromwell Argus, Volume I, Issue 4, 1 December 1869, Page 3

GLACIERS AND GOLD.

LECTUUr BV JA'<E3 ASHCROFT, ESQ., M.P.O. titled as above, was delivered , A j«mes Ashcroft, Esq., M.P.C., on liursday evening last, in aid of the funds |the Cromwell Pul die Library. The atndance was very fair, although not by K’ means so large as the aide and inter* ng lecture which was delivered warnted. Mr W. H. Wlictter, J.P., took e chair, and in a few appropriate words traduced Mr Ashcroft to the audience. r e regret that a want of space will not low us to publish more than a mere outne of the lecture, as it is a subject of very ■eat interest, more especially to a mining ", immunity. Mr Ashcroft, in commencing his lecture, lid that no doubt many present would ke him to answer two questions before s proceeded any further, viz., What is a lacier ? and, What have glaciers to do ith gold 1 In answer to the first question e would state that “ a glacier is a vast iece of ice which forms in the valleys beveon high mountain ranges, and having motion proper to itself through the exansion of. its bulk by heat and other aises, carries along with it in its slow, at almost irresistible course, immense lasses of rock, which are broken from the )ps and sides of tho mountains during its regress.” The lecturer then gave extracts :'Oiu the works of Dr Hochstetter, descripivc of many of the large glaciers in tho or them part of this island visited by Dr Taast and himself at various times. The ocky cliffs of one of these immense masses f ice, visited by Dr Haast in 1861, were 00ft. high, almost vertical, and showed lainly-streaked slips, a proof tint the lacier must have been much higher in ornier times. Another glacier, in the eighbourhoocl of Mount Cook, called the beat Tasman glacier, is described by Dr loehstetter as being eighteen miles" in ength, with a breadth of two miles at its erminal Lice. It is the largest glacier .yet liscovered in New Zealand. For a disancc of two miles this glacier is entirely lovered with an enormous load of rocks md debris, so that the ice is only now and hen visible. “ Now it is apparent (con-, inued the lecturer) that these immense nasses of ice, carrying along with them mmonse quantities of detritns—rooks and 'tones torn from the mountains—must bully deposit their load somewhere, and s we accordingly find what are called lateral md terminal —rocks piled and tumbled one over the other in every conceivable manner. * * * * It is now becoming pretty well understood by scientific men that the same action which now visible in places more or less fe- . [note from the more temperate regions of the earth, and at elevations more or less considerable, has been going on over vast regions where there no longer rests a vestige of tho ice and snow which has done the work. In order, then, to establish the fact of glacial action having extended over wide regions not now subject to it, we have to suppose some climatic changes, or a greater degree of elevation, and it will bo readily seen that the change, so far as New Zealand is concerned, need not have been very great, since even now icebergs approach within 500 miles of our shores, and glaciers extend, in the. northern portion of this island, to within a few miles of the coast.” Tho lecturer then went on to refer to the evidence which existed as to the great change which had evidently taken place in the elevation of the land in this Province, mentioning the fact that fossil shells, teeth of marine animals, ike., jhad been found at a height of nearly 2000 jfeet above the level of the sea. He stated [that in this view he, was strongly supported -|by the opinion of Mr J. T. Thomson, the ■present Chief Commissioner of Crown ■Lands, who had pointed out in the fol|lowing words what must profil'd « then have been the state of things :—“ Glaciers to have floated over tho surface of this island—as their drifts prove them to have {done—must have required that tho land j was then 3000 to 4000 feet lower than it j is at present. The Dunstan and the | Ibnvkdim mountains would then be large id mds, and theKakanni mountains would appear above the waters only as an islet, all covered with snow. At this period, the Te \nau, Wakatip, Hawea, and Wanaka lakes wore solid ice, which, having the motion common to glaciers, ground down the sides and bottoms of their respective valleys, whose lowest extremes stretched out into the ocean, annually detaching and floadug off icebergs, with their accumulated boulders and detritus.” The lecturer quoted other scientific authorities to prove the theory of the great changes effected on the face of nature by glacial action, and continued—“ Having, then, pretty well established the probability of the theory that at some period of time preceding the present era—probably early in the tertiary period—glaciers extended over the whole country, which was then depressed by at least 2000 to ,3000 feet be- ■ low its present level, and having pointed fontJhat the constant motion of these large MjfiUra downwards to the sea would, y”thcy reached the edge of the ocean, (cause large masses of ice to become detached and float off as icebergs with their ; loads of stones and detritus, I have now to I refer to tho consequent effect upon the for..mation of the land as we now see it. Scorosbj plainly shews that icebergs require

water to float them equal in depth to from eight to nine times their height above water. Thus, if an iceberg wera one hundred feet above the water, it would require eight hundred to nine hundred feet below it in order to float it. We may readily imagine, therefore, that the grinding process of which I have spoken would extend a considerable number of miles along the bottom from the main range, which would gradually slope downwards to the sea. These icebergs, exposed alternately to the waves and the ocean currents, tho grinding of the b< ttO a, apd the force pushing behind the m, would disintegrate large masses of rock, would themselves become broken off in pieces, and as warm currents were reached would gradually melt, and deposit the rocks and stones enclosed in them, and in some eases become stranded in the masses of basaltic rock thrown up by the volcanic action from below." In further confirmation of this theory, the lecturer referred to the immense masses of detritus found lying on the solid rock, now that the land has become elevated and the glaciers are only to be found inland, together with large quantities of slate and quartz—the round, smooth portions of rock intermixed with the deposit evidently having been rounded by just such an agent as ice, it being scarcely possible to imagine that hard quartz has been rounded by water alone. We regret that we cannot follow the lee-, turer through the remainder of the first portion of his lecture, which w.ts interesting in the extreme, but our limited spice precludes our doing so. We again quote the lecturer's own words :—" You ail know the matrix or original source of gold is in the primary or secondary rocks—chiefly in the metamorphic schists. These metamorphic schists (continued the lecturer) contain veins of quartz, so generally associated with gold, though I believe not always, inasmuch as gold is found in schists or slates without quartz at all. But, in order to disclose the precious metal to the alluvial miner, a process of breaking-up must first haveoccurred—complete rending asunder and disintegrating of hard, closed textured, solid rock, that would resist the action of. water alone for ages. Accord ingly, we see the miner engaged in sluicing, sinking through deep beds of drift, tunnelling into drift deposited in the sides of hills, bottoming generally on the slate, but sometimes on a later deposit, usually called a false bottom, but winch at the time of the deposit was as true as the other. The heavier deposits of shotty and nuggety gold are, I believe, usually found in these bottoms ; but you are all quite aware that throughout whole districts of this Province one can hardly put a spade in anywhere and wish the soil without finding "specks of gold, which have doubtless been quiefclv deposited from above as the ice in which the broken-up rock rested melted. Wherever, then, the course of the rapid current has been arrested by the spreading oat of the waters into a wide ;>nd comparatively still lake, there, nge after age, has the precious metal been deposited, not solelv or chiefly, as I believe, by the forward flow of the river, but by the sinking in the nearly still water of the heavy metal as liberated during the sum ner months from above. Therefore, while you find richer leads in some particular line, you fin 1 in many places gold * diffused " throughout whole tads and hills of drift, more or les3, from top to bottom." The lecturer here stated it as his opinion that in the extendve flat situated between Cromwell and Bmdigo Gully, some rich leads of gold would yet ba discovered. He thought there could bo no doubt that the whole fl it had taen deposited by g! icial action. an I the vary fact of heavy gold having been procured at the deep lead at tho head of tho flit (in Bjndigo Gully), and also rich deposi s hiving been found at its opposite end, almost warranted the assumption that rich leads of gold would be found scattered through it, although probably at great depths, lie ventured to assert that there was yet a rich future in store, for the Cromwell district, and that at present it was merely in its infancv. Finally referring to the action of .glaciers in New Zealand, the lecturer said—"Thus hive we had at work for us a vast crushing and puddling and sluicing machine, leaving a miss of auriferous conglomerate in the great tail-races of nature for us to wash up. Travelling, as I have recently done, over many miles of similar country, I am astonished at the enormous wealth of auriferous deposits lying all round us and under our feet, capable of affording occupation and the means of livelihood to thousands upon thousands yet to come amongst us. We have but just touched the surface and the very edge of these might v deposits; even leaving out of the question the great storehouses in the hills out of which the auriferous drift has been cut, and which doubtless still contain immense masses of the precious metal. On* almost begins to doubt whether gold will not 'become too common. It cannot 1)3 eaten, it does not wear out very quickly, and' yet wo are ever 'finding more and more and ever increasing our stock of the precious metal. Viewing it, however, as the great medium of commercial exchange, as tho great extender of our modern commerce, which is rapidly Opening up, year by year, fresh channels and new fields of enterprise, we need not be afraid but that

sll wa can get will bo naoded, and that an all-wisa Creator has put it there for beneficent purposes, t having regard to the good of the human race by tho diffusion of population and the spread of civilization and Christianity."—(Loud and prolonged applause.) Mr W. Grant, in a highly eulogistic speech, proposed a. vote of thanks to Mr Ashcroft for his able and interesting lecture, which had bpon listened to with the deepest interest by ■ all. present; and we need hardly say that it was carried by acclamation. Mr Ashcroft returned thanks, and the audience then dispersed.