306 EEPOET UNITED STATES GEOLOGICAL SURVEY. 



foot of a range of liills of 300 to 400 feet in height, which rise from the 

 northern edge of a plateau of volcanic rocks. This plateau is crossed 

 by the Hvita, one of the largest rivers of Iceland, and is about 360 feet 

 above sea level at Haukadal. Within a circuit of two miles a hundred 

 or more hot springs may be counted, although the principal geysers and 

 springs are within an area of a quarter of a mile by 300 feet.* 



The earliest writings in relation to Iceland are silent in regard to the 

 geysers. Are Frode, A. D. 1075, in the Icelandic annals, makes no men- 

 tion of them, although he lived near their present locality. On the 

 other hand, as Henderson says, " it is equally surprising that not the 

 least notice should be taken of their appearance, allowing them to have 

 broken forth subsequent to that period." It must be remembered, how- 

 ever, that in all but highly-civilized nations physical events that do not 

 have an immediate eifect on their worldly interests are viewed with in- 

 difference or apathy. Pliny gives a circumstantial account of the erup- 

 tion of Vesuvius in A. D. 79, but does not mention the destruction of 

 of Herculaneum and Pompeii. Forbes,t from a calculation based on the 

 rate of deposition, gives a probable age of 1,036 years for the age of the 

 Great Geyser. This, however, as I shall endeavor to show in another 

 place (see Part III), is based on an error. 



The earliest mention of the geysers is by Saxo Grammaticus, who 

 wrote in the twelfth century and referred to the Geyser in his preface 

 to the History of Denmark. In the middle of the seventeenth century 

 Svenson, bishop of Skalholt, speaks of the Great Geyser, and says it 

 erupted periodically every twenty-four hours. Since his time a great 

 deal has been written concerning the geysers and hot springs of Iceland, 

 as a reference to the bibliography appended to this report will show. 



In the Haukadal locality there are three principal geysers, viz, the 

 Great Geyser, Strokhr or Stroekr, and the Little Geyser or Eoarer. 



The Great Geyser. — This is the most noted geyser of the world, not 

 only because of the height to which it spouts and the magnificence of 

 the display, but also because it was for along time the only geyser | 

 known to exist, and it was therefore carefully studied by scientific men, 

 and has been made the object of many trips to Iceland. 



It is situated at the northern end of a plateau of deposits at the 

 foot of Laugerfial or Laugafjall, an igneous hill of 300 or 400 feet height, 

 and consists of a bowl or basin, compared by Sir J. Hooker to a saucer 

 with a hole in it, on the summit of a mound of siliceous deposit, above 

 which it rises to the height of 7 feet. The entire mound on the west 

 side is 15 to 20 feet high, and on the east 25 or 30 feet, the slope here 

 being very gradual. On the northwest and south sides the slopes are 

 abrupt. It is about 200 feet in diameter, and the cauliflower-like de- 

 posit is arranged in circular steps. The basin is not quite circular, hav- 

 ing, according to most observers, an indentation on one side. As will 

 be seen Irom a table given a little farther on, the measurements of the 

 basin and tube are variously given by the different observers ; 46 by 56 



■* On tlie map in Mr. John Coles' book (Summer Travelling in Iceland, &c., London, 

 1882) about 50 springs are shown, the space in which they are included measuring about 

 1,600 by 500 feet. 



t Iceland, &c., vol. i, by Ebenezer Henderson, p. 61. 



X Geyser, Geysar, Geiser, or Geisir is an old Icelandic word, meaning gusher or rager, 

 and is derived from the verb geysa or gjosa, to gush, to rage, or to burst forth, to be 

 impelled. In Iceland, in native usage, it is a proper name, being applied not only to 

 the Great Geyser, but also to another fountain at Reykium. The word, however, has 

 become an appellative or common name for the whole class of boiling fountains that 

 spout hot water intermittently, just as the term volcano is derived from the name of 

 one of the vents in the Lipari Islands. 



