"Glaciers.

"Agassiz proves that parts of modern Europe and North America must once have been covered with great fields of ice (1840), Although page 9 his chief study was zoology, yet he could not live at Neuchatel and travel about the Alps without being struck with those mighty rivers of ice called glaciers, which creep slowly down the valley of the Alps in Switzerland, carrying with them stones and rubbish. These glaciers are formed by the snow which collects on the tops of high mountains, and, sliding down, becomes pressed more and more firmly together as it descends into the valley, until it is moulded into solid ice, creeping slowly onwards between the mountains, and carrying with it sand, stones, and often huge pieces of rock which fall upon it. At last one end of this ice-river reaches a point where the air is warm enough to melt it, and here it flows gradually away as water, leaving the stones and rubbish it has brought down lying in a confused heap which is called a moraine. Towards the end of the eighteenth century a famous geologist named De Saussure spent much time in examining the glaciers of the Alps, and pointed out how they are now forming large deposits in the valleys out of these heaps of rubbish which they bring down from the mountains. Since his time many geologists had taken up the study, but it was Professor Agassiz who first spelled out the wonderful history we can learn from it about the former climate of our hemisphere. He noticed that rocks over which a glacier had moved are polished and grooved by the rough stones and sand frozen into the bottom of the ice, just in the same way as a piece of wood is scraped by the sharp iron at the bottom of a plane; and by these glacial cratches or striæ, as they are called, he could tell where glaciers had been, even though there was nothing else to show that ice had ever [unclear: existed] in the country. Now, when he began to examine the slopes of the [unclear: lips] many hundred feet above the present glaciers, and also in places [unclear: where] it is now too hot for ice to remain, he found to his surprise [unclear: members] of these glacial striae, and also remains of huge moraines, [unclear: shewing] that the glaciers of olden times must once have been much larger, and have stretched further down the valley than they do now. And what is still more strange, these same marks were to be seen on the jura Mountains on the other side of Switzerland, where there are [unclear: ever] any glaciers at present; moreover, on the Jura there were found large blocks, some of them as big as cottages, which were not made of [unclear: the] same materials as the hills on which they rested, but were broken [unclear: pieces] of rock such as are now only found on [unclear: the] Alps. It was clear, when, that these enormous pieces of stone must have been carried right [unclear: across] Switzerland from the Alps near Mount Blanc, and across the lake of Geneva, which is 1000ft. deep, and then deposited on the Jura [unclear: large] near Neuchatel, where one block of Alpine gueiss [unclear: their] the ferre-a-Bot, as large as a good-sized cottage, sits perched on a mountain [unclear: 600ft.] above the top of the lake. How had these blocks travelled [unclear: across] the Swiss plains? No flood could have carried them for they [unclear: were] too heavy, and besides they were not smooth as stones are which [unclear: have] been rolled in water, but were rough, with sharp edges. Agassiz [unclear: was] convinced, therefore, that they must have been carried by ice, and [unclear: that] huge glaciers must once have come from the high Alps right across [unclear: Switzerland], filling the Lake of Geneva with ice, and carrying these [unclear: tacks] with them as modern glaciers do now in the Swiss valleys. This [unclear: was] a marvellous history, for it showed that all the lower land of page 10 Switzerland must once have been buried in ice, but other facts after wards came to light which were more wonderful still. In 1840, Professor Agassiz came over to visit Great Britain, and when he went to Scotland with Dr. Buckland, his practised eye discovered at once in the Highlands glacial scratchings, remains of moraines, and blocks which had been carried by ice; and soon it became evident that these were not confined to Scotland, for Dr. Buckland recognised them again in Wales and the North of England, where moraines and erratic blocks are to be seen in all parts of the country. So that here, too, in our little island, there must have been at one time huge glaciers as large as those now found in the Alps. Nor was this all; for when once geologists knew where to look for these signs of glaciers, it began to be discovered little by little that all the Northern countries of Europe Norway, Sweden, Russia, Germany, Switzerland, Northern Italy, England, and even on the other side of the Atlantic—Canada and North America—have been smoothed and scratched; and huge erratic (or wandering) blocks have been scattered over them, shewing that in very remote ages (yet still while very nearly the same kinds of plants and animals as now were living on this globe) the temperate parts of our Northern Hemisphere must have been intensely cold, causing a great part of these countries to be covered with great fields of ice, as Greenland is in the present day. And just as we see now that icebergs break off from the Greenland glaciers, carrying with them stones and mud and dropping them at the bottom of the sea, so in those times icebergs floated over many of the valleys of Europe which were then submerged beneath the ocean. You may see in the railway cuttings of Wales and in the sea-cliffs on the coast of Yorkshire and Norfolk, huge masses of glacial drift, as it is called, made of mud and stones confusedly mixed together, which were dropped from icebergs travelling south wards from the ice fields."

I remember an amusing example of the incredulity with which this remarkable doctrine was at first received. In one of Hugh Miller's books, "The Testimony of the Rocks," he mentions that he pointed out such a carried block to a shepherd, and told him it was brought by ice from mountains 100 or 200 miles away. He replied: "Na, na! that's just where God created it." A friend told me a similar story of erratic blocks near Te Anau, and when he remarked: "I can't think how [unclear: ou] earth they got there," the man to whom he was speaking said: "I expect they just dropped from the cloods!"

Perhaps two facts will help you to receive the theory with more credulity:—(1) We are but 1600 miles from the great region of perpetual ice in the Antarctic. (2) We have glaciers now existing on our western coast, extending quite closely to our sea shores, in the Sounds and on our Alpine range within 200 miles of the eastern coast. Among the various New Zealand authorities, I shall select from the [unclear: picturesq] sketches of the late Sir Julius von Haast, on whom I shall rely for my descriptive facts, Here some of my readers may ask: "What is a glacier?" A glacier is a mass of ice filling a valley, cutting its onwards with enormous force, carrying slowly along in front of [unclear: image not readable] masses of rock known as its terminal moraine, and on its sides other masses known as the lateral moraines. Slow as its movement page 11 is—probably not more than 25 feet in the year—it has immense cutting and grinding force. A glacial river descends from its terminal face under an arch, carrying with it and further disintegrating the moraine matter, and supplied with material from the snowy mountains along its course. Glacial action is characterised by U-shaped grooves in contradistinction to the V-shaped groove of a Intercourse in any hard material; by striae, or markings on hard rocks; by polished faces along its sides where the rocks are hard; by drift containing masses of hard boulders and broken rocks at places far beyond their natural habitat; by angular pieces of rock cut across the natural cleavage; and by roches moutonnèes, or sheep backed—i.e., pounded hills along their ancient courses. All these are more or less present as evidence of a great extension of the present glaciers in former times all over Canterbury and Otago. Now let us hear Von Haast. In his descriptive work on the geology of Canterbury there is a great deal about glaciers, but I will only trouble you with three extracts:—