94 J. S. GARDNER ON THE TERTIARY 



journey of 30 miles along one of these mountain walls. The oldest 

 basalts are not columnar, and are very compact. The whole series, 

 up to the rhyolitea at least, was spread out in vast and almost hori- 

 zontal sheets, and I saw no indications that any were submarine, 

 except some of the newer beds towards Reykjavik, which occasion- 

 ally contain sea-shells among the indurated tuffs. They are utterly 

 different in appearance from the recent lava-flows, which always 

 follow the directions of valleys or water-courses, and it seems im- 

 possible that they could ever have been erupted from craters, no 

 matter of what magnitude. The recent volcanic eruptions are as 

 utterly independent of the Tertiary system of erupted rocks as an 

 outburst in Ireland, at the present moment, would be independent 

 of the basalts there. They are all Postglacial and fresh-looking, 

 while the Tertiary rocks have been, without exception, eroded on a 

 stupendous scale and subjected to ice-action. 



As would be expected, from the fact of their being on such a 

 different horizon, the fossil plants of the Icelandic Tertiaries differ 

 very essentially from those of Ireland and Scotland. The Irish 

 plant-beds are all below the horizon of the columnar basalts, and 

 from their similarity to the flora of the Heersian stage of Gelinden, 

 in Belgium, they cannot be assigned to a later date than the older 

 Eocene. The Mull flora, on the contrary, is situated above some of 

 the columnar basalts, and has already lost the Heersian character- 

 istics, but is still probably of Lower Eocene age. The Icelandic plant- 

 beds are very much newer, and might, from their general character, 

 be assigned to even so late a stage as the Miocene. Some 40 species 

 are recorded, but there are only a few that seem to rest on a sure 

 basis, among them being Abies, Alnus, and Acer. I was not fortu- 

 nate enough to bring back any extensive collections, but I have had 

 an opportunity of examining, at Copenhagen, those that exist. 



Notwithstanding this comparative failure, I do not feel discou- 

 raged, but firmly believe that very great results in this direction 

 might attend another visit, especially to the north-west peninsula, 

 to which I have not yet been. Had I been provided with a tent 

 and stores, I might have made longer stays on the spots where plants 

 are likely to occur. Sir Joseph Banks, in his * Letters on Iceland,' 

 1780, p. 11, speaks of petrified leaves at Eeikum, some of which, in 

 black shale, were brought home. Two localities on the north-west 

 peninsula are mentioned in the ' Flora foss. Arctica,' vol. i. In 

 Olafsen's * exhaustive account there is a precise description of the 

 Surturbrands of Bardestrand, associated with which is a bed of greyish 

 slate divided into laminse from 3 lines to ^ an inch thick, and con- 

 taining leaves, among which oak, birch, and willow were easily distin- 

 guished. Besides these there were leaves as large as the palm of 

 the hand, which had preserved their minutest venation. The leaves, 

 he says, could with care be removed entire, though as thin as paper. 

 Nine other localities for lignite in this region are mentioned, several 

 of which must be worth investigating. 



[I called attention in ' Nature,' August 2, 1883, to two instances 

 ^ Vol. ii. p. 393. 



