William Lord Watts
Across the Vatna Jökull
It may now be as well to take a retrospective view of Iceland to determine the opinion we have formed of the Icelanders themselves, and sum up the leading physical features and characteristics of the country. Iceland, apart from its historical and literary fame, which it is not our purpose to consider, is of especial interest to the geologist and the physical geographer. It lies almost at the northern extremity of the great volcanic line which skirts the extreme west of the Old World, extending from the island of Jan-Mayen in the Arctic Ocean, through Iceland, the Faroe Isles, Great Britain, the Madeiras, the Azores, the Canaries, along the west coast of Africa, right away down to the Antarctic island of Tristan d'Acunha; and its equal as a centre of volcanic activity can alone be found amongst the islands of the Pacific Ocean. The peculiar manner in which we here find ice and snow mixed up with the igneous productions of its volcanoes imparts a grim beauty to its scenery, that I can well imagine we might travel the whole world over without seeing surpassed. A very short sojourn amongst the weird rocks of Iceland arouses that latent superstition which will lurk in the minds of even the most materialistic, and while we laugh at the mythological credulity of the ancient Icelanders, we cannot help acknowledging that a more fitting place to create an implicit belief in wraiths and demons could not possibly be found, all the way from the elf and pixy dancing amongst the timid flowers, whose bright eyes peep from sheltered rocks in ancient lava streams, to the hobgoblin and the ghoul, moaning and shrieking and performing their nameless deeds upon blasted peaks and barren mountain-tops, where fire strives with frost.
This remarkable little island was colonized 1002 years ago by Norwegians, though its earliest settlement is involved in some obscurity. It afterwards became subject to Denmark, until the year before last, when it received its legislative freedom. The Icelanders are upon the whole a harmless, struggling race, and like most other nations that have been unable to draw upon the arteries of other countries for renewed vitality, are encumbered with that contentment which, however conducive it may be to domestic ease, is fatal to advancement. The last twelve months, however, have introduced the element of enterprise which before was only conspicuous by its absence. This may result from their newly acquired liberties or the reflective influence of emigration; at any rate it augurs well for Iceland, whose emigrants have already shown that the Icelander contains a good deal of the right sort of stuff in his composition, and the determined pluck of those who accompanied me across the Vatna Jökull shows us that the spirit of their Viking forefathers, who visited both Greenland and America long before ' the birth of Columbus, is not yet extinct. Preeminently perhaps in the Icelanders' character stands love for his country. It is a remarkable fact that the more barren and unfruitful a country is, the stronger seems to be the attachment and love of the sons of its soil. This trait appears very strongly in the Icelanders' national song, the first stanza of which runs thus—
There is great room for improvement in the home industries of the country, especially in the art of cheese-making, for the milk is rich and excellent, and there is no reason why cheese should not be produced in Iceland that would find a ready sale in European markets. The Icelandic wool, which is unsurpassed, might be likewise worked at home during the winter to a much better advantage; for many choice woollen productions which would command a high price have long ceased to be manufactured. There is also room for improvement in the breeding of stock, and much valuable grass-land might be reclaimed by proper drainage.
The climate of Iceland is very uncertain, but it is much milder than might be expected from its latitude. This is doubtless owing to its insular position, and the influence of the Gulf Stream, one arm of which touches its southern shore. The summer begins in June and ends in September, and during those months the climate is very similar to that of the north of Scotland. The rainfall, especially in the south of Iceland, is very great during the summer, but thunderstorms seldom occur except in the winter. Upon the mountains the climate is still more variable, and I have sometimes experienced a variation of sixty degrees between day and night upon the snows of the Vatna Jökull, at the height of some 4,000 feet above sea level. But few vegetables can now be grown in Iceland—a modicum of potatoes, turnips, radishes, and cabbages alone eking out a struggling existence against an adverse climate, and seldom attaining to what we should consider maturity. The trees of Iceland are mere bushes of birch, willow, and a little ash, and even these are but rarely met vith. The chief exports of the country are fish, oil, tallow, wool, horses, sheep, and Iceland spar, but it is to be hoped (now the sulphur mines in the north of Iceland are about to be worked) that in the course of a year sulphur may be added to these. The imports are some of the luxuries and a good many of the necessaries of life. So much for Iceland itself; we will pass by its history, people, exports or imports, and forthwith consider its physical characteristics ; these may be defined as the volcanoes of Iceland and their products, the hot springs, the Jökulls, or ice mountains, and their effects upon the climate. Iceland contains no less than twenty-two mountains that have been witnessed in active eruption during historical times. The best known volcano is Hekla. This remarkable mountain rises directly from a plain that has been devastated by its repeated eruptions. As the mountain is approached from the north-west its form appears to be that of an oblong cone; it is about twenty miles in circumference, and 5,000 feet in height; it is capped by three smaller cones, the product of recent eruptions. Its craters are all upon the west and south-west sides, and most of its lava streams have flowed in that direction.
The next best known of the Icelandic volcanoes is perhaps Kötlugjá, which has erupted no less than fifteen times since the year 900. It now presents nothing but a deep valley filled with snow, cutting into the very heart of Myrdals Jökull; it is one of the largest examples of breached craters in the world. The principal phenomena attending eruptions of this volcano are stupendous floods of heated water and the prodigious quantities of sand ejected. It has, I believe, never been known to produce lava, but upon the base of the mountain I found numerous ancient lava streams, proving that at one time Kötlugjá was no exception to its neighbouring volcanoes. The floods from Kötlugjá during eruptions have often submerged a district of 280 square miles, continuing sometimes for days, in spite of the rapid outflow to the sea. These floods are produced not only by the melting of the snow at the time of eruption, but in all probability by the bursting of large cavities in and beneath the mountain, in which water might have been for years accumulating. This aqueous phenomenon is, however, by no means peculiar to Kötlugjá, although it occurs on the largest scale, for during the 13th and 14th centuries all the volcanoes in the south of Iceland erupted water. The most extensive eruption that ever occurred in Europe during historic times proceeded from the south-west portion of the Vatna, named the Skaptar Jökull. This volcano has only been known to have erupted upon that occasion, viz., A.D. 1783, when it produced two of the most extensive lava streams in Europe. The highest volcano in Iceland is Öræfa Jökull, which reaches the height of 5927 feet.
The volcanoes which erupted so violently in the spring of 1875, and one of which wrought such damage in the north of Iceland, are—the Öskjugjá (or the chasm of the oval casket), situated in the Dyngjufjoll mountains upon the north of the Vatna, and a chasm some twelve miles in length, which opened in the Mývatns Öræfi (or sandy desert of Mývatns), but as these have already been described at some length I need only casually mention them.
Having briefly enumerated the more important volcanoes of Iceland, we will now consider their products. First there are the agglomerates, which form such an important feature in the geology of Iceland, formed either directly by debacles at periods of eruption, or indirectly by streams and atmospheric influences. Secondly we come to the lavas; these occur either as stony streams that have flowed from the volcanoes, or as pumice which has been hurled high into the air and fallen in a destructive shower of vesicular cinders. Another class of lavas we must likewise mention, namely, the glassy, but we must for the present confine ourselves more particularly to the physical geology of Iceland, leaving the character of the Icelandic rocks for other consideration. Of the stony streams of lava we have two very good examples; first, the huge lava streams which flowed from Skaptar Jökull in 1783, being 50 miles long and 15 wide; and the other 4.0 miles in length and seven broad, being in some places 500 feet in depth. It has been computed that the entire mass exceeds in bulk that of Mont Blanc. This lava is basaltic and highly ferruginous, and impregnates very strongly the waters of the river Eldvatn, which flows through it. The second example is the lava stream which has flowed into the far-famed valley of Thingvellir, wherein the Althing, or Parliament, of Iceland used to hold their meetings, and the wonderful rifts of the Almanna-gjá and the Raven's-gjá occur. At some remote period of the geological history of Iceland a large river of lava flowed from Mount Skjaldbreið, which is about thirty miles distant, into the valley of Thingvellir; a crust, of course, soon formed on the surface, and upon the cessation of the eruption, the still liquid lava at the bottom of the stream continued to flow into the deeper parts of the lake which occupies the south-east end of the valley of Thingvellir, leaving the unsupported crust, which was now of great thickness, to sink down to the present level of the valley, occasioning lateral rifts upon either side of the stream, viz., the Almanna-gjá on one side, and the Raven's rift upon the other. The valley of Thingvellir is likewise traversed by many smaller fissures and crevasses, which in many instances enclose and almost insoculate large masses of lava; the Logberg, or "hill of laws," is sucli an island of rock, and is rendered inaccessible, except at one point, by deep yawning crevasses. It was on account of these natural fortifications that it was chosen as a forum for the ancient court of Althing, which assembled there once a year. Such are the monuments of Iceland, which take the place of the ruined castles and abbeys of other countries, simply the rude rocks of nature ennobled by brave deeds of history or some touching romance of love.
We now come to the hot springs of Iceland. The chief of these, par excellence, is, of course, the Great Geysir; it has been so often described and redescribed that it scarcely needs a remark from me. Professor Forbes calculated its age, from the thickness of the siliceous sinter which surrounds its basin, at 1000 years. The Great Geysir is surrounded bv numerous other springs of all temperatures and sizes, whose deposits differ according to the character of the rocks through which they pass. There aro numerous hot springs scattered about in various parts of Iceland, some of which owe their existence to earthquakes, which instantaneously called them into being—in 1339 a hot spring sixty feet in diameter suddenly opened at Mosfell — and during the earthquakes which preceded the great eruption of Skaptar Jökull in 1783, no less than thirty-five new hot springs made their appearance. We may not dwell longer upon these interesting phenomena, but we will turn our attention to the huge ice mountains or Jökulls of Iceland, which constitute such an important feature in the physical geography of the country. The principle ones are the Vatna, Arnarfells, Hofs, Lang, Myrdals, Godalands, Eyjafjalla, Dranga, and Glámu Jökulls. Of these remarkable features in the physical geography of Iceland we could not find a better example than the Vatna Jökull, which has formed the principal subject of this little book : until recently it was almost a terra incognita, and until this year had resisted all attempts to cross it.
The Vatna Jökull is a vast accumulation of volcanoes, ice, and snow, comprising an area of over 3000 square miles. It is for the most part surrounded by a wilderness, formed by the destructive outbursts of its volcanoes, and the constant drifting of the glacial torrents which flow from its melting snows. The Vatna Jökull and its immediate surroundings constitute the most lofty portions of Iceland, and I believe the oldest, for we find lava streams which have flowed from its volcanoes in a state of ruin and decay unequalled in any other part of the country ; and, again, we find it bounded upon the south by sea cliffs that were washed by pre- historic oceans when many other parts of the island must necessarily have been under water, unless very serious depressions have taken place since the waters which washed the south outlying hills of the Vatna receded to their present limit. The Vatna Jökull comprises by far the most important mountain section in Iceland, and a far greater area is covered by its snows than could be occupied by the sum of all the remaining snow-clad mountains in Iceland. As may be supposed, perhaps half the river water of Iceland flows either directly or indirectly from the Vatna Jökull, either issuing in torrents from the extremity of its glaciers, or, after filtering for long distances through the loose and cavernous ground, appearing as land springs at a lower elevation.
The rocks of the Vatna, as far as I have had an opportunity of judging, are purely and simply the product of this very remarkable cluster of volcanoes, which have piled up layer after layer of ash, sand, and agglomerate, until a mountain heap was formed of such a height that it allowed snow and ice to accumulate upon it to such an extent as to render the summer's warmth quite inadequate to remove it. This vast snow pile then grew of its own accord, and glaciers commenced to creep down the sides of the barren mountains upon which it rested. Volcanoes continued to erupt, but the effect of their fires upon the accumulating snow must have been purely local and limited in the extreme; for volcanic productions are the worst possible conductors of heat, and I should imagine that a lava stream, unless it be of gigantic proportions, conducts itself beneath the profound snows of the Vatna much as a lava stream would beneath the sea, without producing any very violent commotion. Thus this vast mountain mass was accumulated, growing with each succeeding winter and each eruption. The Vatna Jökull rises by a very gradual slope upon the south, and it is not until more than thirty miles of snow fields have been traversed that the highest part of the Vatna, viz., 6,150 feet, can be reached from that direction.
I have at present omitted any mention of the snow line in Iceland; this is on account of its variable nature, incidental to local causes. Thus upon the Vatna we have the snow line much lower upon its southern than northern slopes, the cause of which we will consider presently.
Of late years the volcanic forces of Iceland appear to have retreated to the Vatna Jökull and its immediate neighbourhood, and volcanic eruptions have been witnessed in force in several directions. The Kverkfjall we found to be smoking and Öskjugjá can only be regarded as a lateral crater of the Vatna, and, I doubt not, had we been favoured with better weather, we should have found many other eruptive vents; but so rapid is the accumulation of snow upon the Vatna, and so bad a conductor of heat are all volcanic eruptions, that the traces of them are very soon obliterated. As may be supposed, such a prodigious accumulation of ice and snow as the Vatna Jökull produces a very sensible and marked effect upon the climate of cer- tain parts of Iceland. It has this effect—it deluges the country to the south of it with rain, and gives to those districts which lie to the north of it a hap- pier climate than they would otherwise possess. The snowy heights of the Vatna attract to themselves the aqueous vapours which travel northwards from more southern latitudes, depositing them upon their broad shoulders in the form of snow and hail, and refrigerating and drying the vapours which travel across their snows, thus rendering the south wind a wet one in the country to the south of the Vatna and the north wind a dry one, whilst in those districts which lie to the north of it the reverse is the case. And since by far the greater part of the aqueous vapours which reach Iceland are borne thither from the more readily evaporating waters of southern oceans by that bugbear to travellers in the south of Iceland, the southerly wind, we see at once why the snow line is lower upon the south than the north of the Vatna Jökull. When we inspect the glaciers which fringe the south of the Vatna Jökull, we find they have decidedly advanced; indeed, at one point so much so as to almost destroy communication along that part of the south shore. Upon the north we find that a huge tongue of glacier has flowed down full ten or twelve miles beyond the utmost limit assigned to it by Gunlaugson some forty years ago, while the route traversed by that enterprising man is completely overrun by the ice, and the traditionary road of the Vatna Jökull's vergr is now amongst the high snows of the Vatna.
Icelanders, as a rule, are loth to admit the advance of their glaciers, and vainly appeal to striated rocks at much lower altitudes than most of the Icelandic glaciers of the present day, and . to moraines stranded upon the plains beneath some of the principal mountain sections; but since it is impossible to say when these rocks were scratched, or even whether the very rocks to whose striae they so, confidently point were not erupted long before Northern Europe and America disappeared beneath the ice and snow of the earlier glacial period, what is the use of such evidence ?
The very moraines may have been produced by the glaciers which have strewn even our own country with erratic boulders . and glacial débris. Again, it is no uncommon thing in Iceland for huge masses of glaciers to slide down the mountain side during periods of eruption, scratching the harder and furrowing the softer rocks in their progress, and leaving heaps of débris in no way distinguishable from terminal moraines. These facts are rather startling. True, the glaciers of Iceland may, and, no doubt, do ebb and flow, but they gain upon the whole, and never would increase to this extent was not the annual accumulation vastly in excess of the waste. It may be said this is due to a cycle of unpropitious seasons. Possibly ; but we find this advance of northern glaciers is not peculiar to Iceland. Dr. Nordenskjold has proved a considerable advance in the glaciers of Spitzbergen ; Greenland gives us the same intelligence. This seems to point to something more than a local advance, compensated for by a retreat in other places. It is too rapid an advance to be accounted for by astronomical causes; but cannot we suggest some comparatively slight physical changes which may account for it? Granted that above a certain latitude the earth only receives as much heat during the summer as it does during the winter, and that in one winter it will accumulate just as much snow and ice as the summer's heat will suffice to melt, if it were all employed for that purpose. Now we are perfectly aware that snow and ice having once accumulated, a greater part of the succeeding summer's heat would be reflected back into space and not employed in melting them, while the aqueous vapours condensing above it would screen the snow from solar influence.
Thus a new glacial period would creep upon us, heralding its approach by an advance band of low temperature of its own production were it not for the warm oceanic and atmospheric currents, for the beneficial influence of which we have only to look at the varying temperature of many localities in similar latitudes to appreciate. A great alteration in temperature and climate would certainly take place supposing any variation should occur in the direction of these currents—in the Gulf Stream, for instance. Supposing that its waters, instead of reaching so far north, were deflected southwards, then not only would Arctic climates and Arctic ice be less affected by it, but the deflected stream would heighten the temperature of the waters of lower latitudes, and cause an increased evaporation ; consequently there would be an increased condensation upon northern mountains and Polar shores, and an increased reflection of the succeeding summer's sun. It is rather a curious fact that less American driftwood has been brought to the northern shores of Iceland during late years, and an increased amount has been cast upon its southern coast. This little fact of course proves nothing in itself; but when we see northern glaciers advancing to the extent they have done one naturally asks the reason. Astronomical causes we must put on one side, for the glacial advance is too rapid to admit of that solution. But if northern glaciers continue to advance, it will be a matter of some interest if we could ascertain whether those mysterious forces which give birth to the earthquake and the volcano have wrought any alteration in the flow of that guardian angel of the north — the Gulf Stream.
We will now pass on to the volcanic rocks of which Iceland is constituted. The foundation of Iceland is palagonitic tuff of sub-aqueous origin, disturbed and at times metamorphosed by enormous masses of amygdaloidal basaltic lava whose cavities abound with zeolites, being traversed by dykes and layers of interjected basaltic and trachytic lava at all times dislocated and confused by the various earthquakes which from time to time have shaken Iceland to its nethermost stone. These rocks are overlaid by lava streams of sub-aerial origin, pumiceous tuffs and agglomerates that have been formed by debacles and atmospheric influences. Concerning the strike and dip of the various layers of trap and basalt there is no general inclination, no uniformity — all is confusion. The loose soil of Iceland is entirely composed of disintegrated and decomposed volcanic rocks and decayed vegetable matter, and would be very fruitful if it were in a lower latitude. The vast period of time which it must have taken to decompose the huge lava streams that we find almost entirely converted into humus may be appreciated when we look upon pre-historic lava fields, grey with lichens, like that of Thingvellir, while the actual decomposition of its surface scarcely amounts to half-an-inch. We may divide the lavas of Iceland, like those of most other volcanic districts, into two classes; first, the basalts passing into dolerites, and secondly, the trachytic lavas. The more ancient basalts occur most frequently as intruded masses of amygdaloidal character; the doleritic lavas of Iceland are the more recent products of its volcanoes, varying only in this respect, that the earlier erupted lavas contain crystals of olivine, in addition to the felspar and augite which occur in most of the lavas of our own time.
Trachytic lava occurs but sparingly in the parts of Iceland that I have visited. It has for a long time been assumed that a trachytic band was disposed upon a fissure which bisected Iceland from N.E. to S.W., namely from Cape Langanes to Reykjanes upon which the principal centres of eruption were supposed to be situated. This, how- ever, is a presumption unwarranted by investigation. A glance at the map will show us that there are many other centres of volcanic activity which do not occur in this imaginary trachytic band. True most of the more recently active volcanoes occur upon this rectilinear, but there are Myrdals Jökull, Eyjafjalla and Öræfa Jökull, all volcanoes that have erupted comparatively recently, and a host of more ancient volcanoes distributed over other portions of the island, which might lead us to surmise that there were a dozen instead of one great fissure in the superficial rocks of Iceland.
Trachytes, principally I believe in an altered condition, have been found around and between Hekla and the Geysers, and notably at the volcano of Rauðarkamb. I was informed, however, that we must look for the greater part of the trachyte of Iceland other than in a pumiceous form upon the peninsulars of Snæfells Jökull. Certainly I found that trachytic lava almost died out upon the north side of the Vatna Jökull, or else it is so covered up with recent volcanic productions as to be undiscernible. The obsidians of Iceland, which are found so universally distributed in fragmentary forms upon the sides of the volcanoes are seldom to be met with in situ, indeed the only instance that I have met with of obsidian in situ was at Mount Paul, in the heart of the Vatna Jökull. That mountain, as we have already seen, is entirely composed of obsidian, varying from the vitreous to the grey stony variety.
The obsidians of Iceland seldom contain the beautiful felspar crystals, so characteristic of the Arran pitch-stones, but «ome of them are of a porphyritic nature, showing under the microscope crystals of quartz much fissured and split about, no doubt during the process of cooling. We must also regard the greater part of the pumice which was ejected last year from the Oskjagja as an obsidian, in spite of its remarkably vesicular character. The fine dust which was carried to Norway during the eruption of last Easter-day resembled powdered glass, and led geologists there to come to the conclusion that the mountain which was erupting must have been pouring out great quantities of obsidian. As compared with the lavas of Vesuvius, I cannot help suggesting that many of the more ancient lavas in both instances are of a more trachytic and porphyritic character. In the Vesuvlan lavas especially, the crystals contained by the older rocks have crystallized out of the uncrystalline or semi-crystalline mass. A prevalent mineral in the older Vesuvian lavas is leucite, which corresponds to the olivine that occurs so frequently in the older erupted lavas of Iceland, while those minerals are seldom to be met with in the more recent lavas of either Iceland or Italy.
I must now bring these few pages to a close. I dare say they contain a great deal of what is not worth reading; but as they give the only account of the Vatna Jökull and the part of the Ódáðahraun which I traversed, I trust those that may take the trouble to read them, will accept them as the best and the most accurate account of those districts that I am able to give.
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