Page:Quarterly Journal of the Geological Society of London, vol. 34.djvu/105

Rh that nevertheless he had realized results of very considerable importance. He referred to Prof. Heer's notion that a migration of certain plants had taken place since Miocene times from north to south, and pointed out that the existing North-American flora more resembles the Miocene than its own Pliocene flora. An examination of the Echinodermata brought home by the Arctic Expedition had led him and Mr. Sladen to the belief that these also furnish indications of there being a polar zone of Echinoderms.

Capt. exhibited a photograph and gave some account of the locality from which the plant-remains were brought. He stated that shales and sandstones similar to those overlying the lignites were found lying directly on the older schists in other neighbouring valleys, and that in some instances fragments of lignite occurred in them, and suggested that probably the whole of the valleys here were at one time occupied by deposits of the same age.

Prof. remarked that after listening to all that had been done in the investigation of Arctic floras, it was impossible not to feel convinced that we only require to get hold of the right clue in order to make out a great deal. He said that he could not believe that plants such as Sequoias, Figs, and Vines could live through the long night of an Arctic winter and flourish again the following summer. He thought that the gradual accumulation of palæontological facts was gradually leading to a general opinion that there must have been a change in the direction of the axis of the earth with respect to the sun's light; and if, as he understood, Prof. Heer believed that plants had spread from north to south, it seemed to him that this was strongly in favour of a change in the direction of the polar axis.

Mr. said that Capt. Feilden had referred to a dying-out of species as we advance towards the pole, and suggested that if this be real, it may be due to our explorations northwards lying in the same direction as that taken by the pole in its movement southward. The variation of level mentioned to the extent of 1000 feet, might throw some light on the question, as it might be due to a change in the position of the nucleus of the earth with regard to its surroundings.

Capt. Sir referred to the presence of vast fluviatile deposits close to the bed of lignite.

Dr. thought that too much stress was laid upon the influence of the sun's light in this question, and referred to the fact that tropical plants are preserved and flourish in St. Petersburg in spite of the long dark winter. He suggested that changes in electrical conditions might have some influence on the possibility of the existence of life at the poles.

Prof. inquired how far round the arctic circle we can find evidences of such changes as are assumed. If the changes in the position of the pole were geographical, it was clear that the Miocene vegetation could not approach the pole all round at the same time.

Mr. remarked that the onus probandi rested, not with the geologists, but with the mathematicians, upon whom it was incumbent to show how plants could grow at the points where their