The Geysir field is situated at the northern edge of the southern lowlands, at an altitude of 105-120 m above sea level. Until recently, the area was called Hverasandar. The hot springs are located to the east of a little mountain called Laugafell.
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The geothermal field in Haukadalur lies on the outskirts of the neovolcanic zone from which it is drifting, and is therefore gradually becoming a low-temperature field. Magma may have forced its way out of the neovolcanic zone along one or more fissures, forming intrusions. This would explain the sustained geothermal activity. There is no evidence of recent (holocene) volcanism in this area and the bedrock appears to have been formed subglacially towards the end of the glacial period.
The geothermal field is believed to have a total surface area of approximately 3 km². Most of the springs are aligned along a 100 m wide strip of land running in the same direction as the tectonic lines in the area, from south to southwest. The strip is 500 m long and culminates near what once was the seat of the lords of Haukadalur. Today we find a church there. Here and there, at a considerably shorter distance from the ancient seat than from the hot springs, we find a 20-150 cm thick layer of siliceous sinter, mostly covered by earth, or in some cases even out in the open as the mound at Hvitamelur. Hvitamelur was once a spouting spring, but it is now absolutely dry. We can still discern the rims of the ancient basin, and the singer safeguards quite a few plant fossils. In other words, hot spring water must have covered large areas from which the geothermal field seems virtually to have moved. The heart of the geothermal area is now 2 km to the south of the Haukadalur seat, but two little springs have been left behind, Marteinslaug and Gufubadshver. As for the centre of the field, the northernmost springs, such as Geysir itself, are believed to be the oldest.
In Geysisgil, situated a little to the northwest of Geysir, a 20 cm thick layer of earth covers an older stratum of siliceous sinter. However, the very same layer of earth passes under Geysir’s sinter. This indicates that geothermal activity has subsided for a time, allowing vegetation to flourish until some event, possibly an earthquake, caused a fracture from which water could emerge again.
The temperature of water 20 m down Geysir’s feeder channel is about 125 ºC. It has risen from a depth of 1-2 km. Geysir discharges 1.5 l/s, whereas the entire area discharges 14 l/s. During the dreaded earthquakes that regularly ripple across southern Iceland, deep fractures inch their way into the country as far as to Haukadalur, yet no known damage to property has as yes been caused this far north. After a seismic swarm, the Geysir springs tend to gather new momentum, particularly the spouting springs, each of which seems to try to outrival the other. Several sources record that after an earthquake, Geysir has spouted impressively at 6-8 hour intervals. Nevertheless, no known seismic fracture leads to the Geysir field, and there is nothing to indicate that the field itself has been the source of earthquakes. Geologists believe that the next round of earthquakes in southern Iceland is relatively imminent, for the advent of these seismic events has been fairly regular for several centuries. So the Geysir field, which has more or less hibernated for quite some time now, might very well be revitalized in the near future. On the upper part of a sloping piece of land called Melar, to the north of and above Blesi and Konungshver, to the northwest of Geysir, we find three stones called Konungasteinar bearing the initials of kings that have ruled Iceland and who have visited Geysir: Christian IX in 1874; Frederik VIII in 1907; Christian X in 1921.
A footpath leads from Konungshver to a panorama disk near the fence. Travellers should make a point of studying the panorama disc, and the view from there is excellent. The view is even better from Laugafell. The walk up the hill should not be too rough for most people. However, Geysir is neither the largest nor the most impressive of the world`s hot springs. It probably secured its eminence by being known to Europeans at an early date, i.e. before the springs in the new world. As soon as the Yellowstone springs were discovered in the 19th century, they were immediately preserved as a national park. The numerous travelogues printed about Iceland almost all pay tribute to Geysir. To this very day, Geysir’s water jets are considered to be amongst the most remarkable natural phenomena in Iceland. Many a traveller has journeyed far to behold them and Icelanders have been proud of them for a long time. More often than not, the earthquakes in southern Iceland have stimulated Geysir, as has been pointed out above. Nevertheless, in time its aquifers have been by incrustations, the flow has diminished and the spouting interval has increased. In 1871 William Morris writes in his diary that Geysir usually only spouts once every five or six days, from which we may infer that its activity had already diminished, and in 1895 Geysir was most unwilling to spout. Sometimes three weeks would lapse between each jet. Major earthquakes on 10th September 1896, gave Geysir a new lease of life and for a while it spouted once or even twice a day, to greater heights than previously. After two or three years following the tremors, it grew sluggish again.
After the turn of the century Geysir grew very listless and in 1916 it ceased to spout entirely. In 1935 a 50 cm deep furrow was carved into the northern rim of the Geysir basin, whereby the spring was revitalised for a few years, but towards the middle of this century it spouted only very rarely. For some years or even decades preceding 1980, Geysir was quiescent. It was no use pouring soap into the vent, even though soap is generally an excellent medicine for spouting springs, as has been mentioned above. In its lethargic state it failed to create much of an impression. Fortunately Strokkur was there by its side, spouting gaily enough to satisfy most spectators. Others waited for a new round of earthquakes to revitalize Geysir. Then something happened in 1981. The furrow that had been carved into Geysir`s rim was scraped clean and enlarged to a depth of 70 cm and a width of 25 cm with the removal of sinter that had accumulated in it. Geysir reacted instantaneously: as its water level dropped, the spring spouted, and continued to do so almost every day until the furrow was covered up and dammed in 1983. Its jets reportedly reached a height of 40-50 m. The furrow was dammed in such a way that it could be reopened. Geysir`s capricious ways have always fascinated its admirers for it never ceases to take them by surprise. Shortly after the middle of the present century, a group of people had waited 8 hours after soap had been administered, but the spring never stirred, so finally the people left. As soon as they were out of sight Geysir produced one of its most spectacular eruptions. A few weeks later, a group of congress delegates, determined to linger for days if need be, arrived to witness the spouting of Geysir at any cost. Soap was administered while they were on their way, so that they would be spared at least some of the delay. When they arrived, Geysir had just relieved itself and all they found was an empty, fuming vent.
Strokkur (the churn) is currently the most energetic spouting spring in Iceland. It spouts every few minutes, sometimes to a height of 40 m, yet generally less than 10-20 m. We know little of Strokkur’s age and past history. It was set off during an earthquake in 1789, having then been quiescent for some time. In all probability though, it had been active before. The year after Strokkur started to spout it was extremely powerful and ejected water, gas and steam with tremendous force. Towards the beginning of the following century it spouted with less frequency, yet with such fury that even Geysir paled in comparison. At the time, Geysir’s jets reached a height of 30 m, whereas Strokkur would spout 40 m. It had, however, calmed down considerably in 1830, and rarely spouted on its own accord, so people had to encourage it with stones and turf, which the spring would subsequently throw up. Thu Strokkur could be persuaded to spout, but rarely more than 20 m. Besides, its water column was a rusty red from earth and turf. After the earthquake in 1896, it subsided completely, but rallied somewhat in 1907, yet not to its previous glorious state. By 1920 it had expired again. On the recommendation of the Geysir committee, a 40 m deep hole was drilled from the bottom of its basin in 1963, after which it has spouted or at least squirted merrily ever since. Discharge from the spring, or rather from the borehole, is currently 2.5 l/s.
To the west of Geysir and above it, we find Blesi (blaze; the word is often used as a name for a horse). It used to spout one metre, but is currently quiescent. Diaries from the last century refer to ‘the brook from Blesi’ where travellers bathed and washed their clothes. Today we can hardly speak of any brook running from Blesi although the spring discharges 1 l/s. Blesi consists of two large basins separated by a spot of land, the ‘blaze’. The southern spring is full of very deep, very limpid, boiling hot and absolutely colourless water, so that on quite days the spring seems dry. From this basin, water flows across the ‘blaze’ to the northern spring which is azure coloured. This blue spring, which is 1 m deep, does not have its own source so its waters are fairly cold, 40 °C.
The azure blue colouring can be seen elsewhere, such as in Bláhver at Hveravellir, and is caused by dissolved silica. When water issues from the ground in the southern spring, silica is already fully dissolved, but does not react before it meets the atmosphere. With a little imagination we might picture ‘Blaze’ as having one blue eye encircled by siliceous sinter. It is possible to bathe in the ‘blue eye’ where the temperature is comfortable and constant down to the bottom. Nevertheless, from an environmental point of view, people should abstain from bathing here. Slightly to the south and below Blesi, we find Fata (the pail) with a shape not very unlike that of a pail. The surface level of Fata’s water varies, and on rare occasions it will even spout. Soap stimulants will make it spout quite beautifully. For some years now, there has been a tendency to let Fata spout while people are waiting for Geysir to spout.
Fata is not very copious, but quite hot. A few hours before Fata is meant to spout, water is made to flow into it from Blesi. When Fata’s basin is practically full, the flow is cut, and the water is allowed to heat for an hour. When it reaches the boiling point, soap is poured in and usually you will not have to wait long before you see the majestic results. Sometimes though, there will be quite a delay while the soap is churned with increasing violence. Finally the boiling becomes explosive and the spouting starts. The spouting goes on for and extraordinary length of time and the jets slant in the direction of Strokkur.
Konungshver (the royal spring) is slightly to the northwest and above Blesi, at the lower and of the footpath to the panorama disc. It is the northernmost spring in the Geysir field, together with Geysir itself. Konungshver acquired its name on 1874 when King Christian IX visited Geysir. Konungshver has never spouted, for its shaft is full of boulders that are clearly visible to anyone who looks into the spring, yet it still growls a little from time to time. With appropriate equipment it should be possible to extricate the stones, and who knows what Konungshver may have up its sleeve. Near the footpath, to the south of Strokkur, Litli-Geysir has been hibernating for some time. But William Morris has seen it in quite a different light, as we may infer from his description written in 1871.
Seidir huddles close to Litli-Geysir. It is believed to have once been one of the principal springs in the area, but has now cooled down. Yet until quite recently it could be induced, with soap, to spout a few metres. Somewhat to the west of it we have Oþerrishola (wet hole), mainly reputed for its meteorological capacity, especially as it can predict rain. When the atmospheric pressure falls, the spring starts squirting, thus giving an idea of how the weather will be in the wake of the depression.
Furthest to the south, slightly to the west of the entrance to the area, we find the springs, Þykkuhverir, that discharge 4 l/s. One of them, probably the most handsome, is called Smidur (the smith). In its sinter basin water is forever churning, and after soap treatment Smidur will spout to a height of 3-7 m. Very little soap is needed. Two litres of a soap solution will suffice to produce a water column just a few minutes later although the episode will be very brief. The spring needs a lot of time to settle down again and it is futile to treat it with soap more than once a day. Just below Smidur, a small nameless spring bubbles violently. After a helping of soap it will fling its water several metres into a slanting jet, but only for a moment, after which the spring’s water supplies are renewed in the course of a few minutes, only to be thrown out again. This cycle repeats itself for nearly an hour until the spring settles down. Slightly to the south, Sodi (the messy one) spouted for the first time in 1940, as far as we know. When offered soap, Sodi’s water columns can attain a height of 20 m. But the cold brooks that flow into Sodi must first be diverted. And considerable soap is needed. One of the westernmost springs in the Þykkuhverir group is Sisjodandi (forever boiling) which, as the name indicates, tends to boil quite tumultuously. Still it never quite manages to spout, as a cliff hems it in. People used to wash their clothes there, even after the middle of the present century. They had to take care not to soak the clothes too long, or else silica would destroy them.