19 197 



traces of sulphates. This spring lies to the extreme south of the alkaline springs 

 here, only 2 m. from the spring examined in 1904 as "Reykjafoss Nr. I"' which 

 seems to be extinct, at least there are no further exhalations. Reykjafoss No. 2 and S 

 come from two small mud pools in Hverageröi, to the south-west. These springs, 

 containing sulphui'etted hydrogen, naturally gave an acid reaction. The fourth 

 sample of gases, Reykjafoss No. 4, was taken from a little hot spring to the east ol 

 Varmd, just below the neighbouring waterfall (Reykjafoss). 



The warm springs around Reykjafoss really constitute the southern part of a 

 larger spring district which stretches towards the north with varying intervals of 

 space, to the east of the highest point of the mountain Henyill. In this district 

 there are solfataras, mud pools, clear, alkaline water basins and geysers, so that 

 nearly all the more general kinds of springs in Iceland are represented here. 



Apart from the springs around Reykjafoss, we were only able to examine the 

 most northerly groups of springs in this district. These are named : — 



Henglahverir. 



Our sojourn at these springs lasted from the 17th. to the 20th. August 1906. 



They are situated on the eastern slope of the mountain Hengill, where a large 

 number of, for the most part, very strong hot springs are in evidence, collected in 

 several separate groups. The distances between the groups are greatest in the 

 direction from north to south; it is in some cases almost 1 km. On the other 

 hand, the differences in their elevation are proportionately much less, in that they 

 are all situated at the place where the slope of the mountain towards pingvalla- 

 vatn lessens. It appears as if the hot springs here resort preferably to depressions 

 in the ground. The southern groups go under the name of Olvisuatnslaugar, while 

 the northern are called Nesjauallalaugar. On the whole, the thermal activity in 

 Hengill is at least as great as at any other of the places we have visited, with 

 perhaps the exception of Kerlingarfjöll. In appearance, these hot springs most 

 resemble the springs at Myvatn and on Kerlingarljöll, in as much as they are 

 either solfataras or mud springs. 



On account of the great number of these springs, I must refrain from a 

 detailed description of them, though they are in many respects highly interesting, 

 and content myself with a summary account of the most important groups. 



To the extreme south there is an isolated mud pool in the centre of a grass 

 plot. One cannot see the spring itself until one is close to it, as it gives off, in 

 contrast to most of the other hot springs, very little steam. On the other hand, 

 one can hear at a distance of 200 m. the rippling sound made by the large bubbles 

 of the gases forcing themselves up through the mud, which is of a pulpy nature. 

 Each bubble is from 1 to 2 litres in size, and when it emerges from the surface 

 and the mud closes in again this peculiar sound is emitted. This mud pool seems 



' K. Prytz og Th. Thorkelsson loc. cit. p. 325. 



26* 



