Krug von Nidda on the Mineral Springs of Iceland. 93 



600 to 700 feet in height. The valley is about a quarter of a 

 mile broad, and its bottom consists of marshy meadow-ground, 

 through which several rivulets follow serpentine courses, and then, 

 at the mouth of the valley, unite with the Huitaae. So far as the 

 eye can reach to the north, nothing is visible but the indestructi- 

 ble covering of ice which envelopes the plateau of the Bald- Ju- 

 kul. Towards the north-east the valley contracts, and through 

 a small opening are perceived steep broken-up mountain masses, 

 which are piled up in gigantic groups in the interior of the 

 island. To the south the three snowy peaks of Hecla project 

 above the rocky wall of the valley ; to the south-west the great 

 plain commences, that extends to the sea. The rocky walls of 

 the valley consist of layers ranged one above another of tuffas, 

 streams of slag, and slag conglomerates; and also of a mass of rock 

 which belongs to the great trachyte formation, and reposes on 

 the trachyte porphyry as a more or less thick covering, so that 

 the last is almost exclusively found forming the domes of the 

 high plateaus. 



A small rocky hill, about 800 feet high, and one-eighth of a 

 mile long, seems to have been violently torn from the steep 

 rocky wall which bounds the valley on the north side. A nar- 

 row fissure-like ravine forms the separation. The hill presents a 

 steep declivity opposite to the rocky wall ; but on the side next 

 the valley, its slope is gradual. On the last-mentioned side of 

 the hill are scattered the celebrated springs, of which more than 

 fifty can be counted in a small space of a few acres of land. 

 Almost every spring possesses its own characteristic features, by 

 which it is more or less distinguished from the others. An essential 

 separation can only be made between the openings that are filled 

 with hot pure water ; and those from which especially the streams 

 of hot gases issue, and which contain 720 water, or very little^ 

 and then only muddy water (mud springs). The first de- 

 serve the name of water springs, and the latter that of gas 

 springs. 



Both kinds of springs, although in each other's immediate vi- 

 cinity, nevertheless differ in regard to position ; for, while the 

 gas springs rise from the acclivity, and even from the summit of 

 the rocky hill, the water springs occur exclusively on the flat 

 surface at the foot of the hill. 



