This is shown (a) By the fact that Captain Inglefield and Dr. Ruik observed trunks of trees standing upright. (b) By the great abundance of the leaves, and the perfect state of preservation in which they are found. (c) By the fact that we find in the stone both fruits and seeds of the trees whose leaves are also found there. (d) By the occurrence of insect remains along with the leaves. 2. The flora of Atanekerdluk is Miocene. 3. The flora is rich in species. 4. The flora proves without a doubt that North Greenland, in the Miocene epoch, had a climate much warmer than its present one. The difference must be at least 29° F. Professor Heer discusses at considerable length this proposition. He says that the evidence from Greenland gives a final answer to those who objected to the conclusions as to the Miocene climate of Europe drawn by him on a former occasion. It is quite impossible that the trees found at Atanekerdluk could ever have flourished there if the temperature were not far higher than it is at present. This is clear from many of the species, of which we find the nearest living representative 10° or even 20° of latitude to the south of the locality in question. The trees of Atanekerdluk were not, he says, all at the extreme northern limit of their range, for in the Miocene flora of Spitzbergen, lat. 78° N., we find the beech, plane, hazelnut, and some other species identical with those from Greenland, and we may conclude, he thinks, that the firs and poplars which we meet at Atanekerdluk and Bell Sound, Spitzbergen, must have reached up to the North Pole if land existed there in the tertiary period. "The hills of fossilized wood," he adds, "found by McClure and his companions in Banks's Land (lat. 74° 27′ N.), are therefore discoveries which should not astonish us, they only confirm the evidence as to the original vegetation of the polar regions which we have derived from other sources. The Sequoia Landsdorfii is the most abundant of the trees of Atanekerdluk. The Sequoia sempairrcus is its present representative. This tree has its extreme northern limit about lat. 53° N. For its existence it requires a summer temperature of 59° or 61° F. Its fruit requires a temperature of 64° for ripening. The winter temperature must not fall below 34°, and that of the whole year must be at least 49°. The temperature of Atanekerdluk during the time that the Miocene flora grew could not have been under the above.* Professor Heer concludes his paper as follows :— "I think these facts are convincing, and the more so that they are not insulated, but confirmed by the evidence derivable from the Miocene flora of Iceland, Spitzbergen, and Northern Canada. These conclusions, too, are only links in the grand chain of evidence obtained from the examination of the Miocene flora of the whole of Europe. They prove to us that we could not by any re-arrangement of the relative positions of land and water produce for the northern hemisphere a climate which would explain the phenomena in a satisfactory manner. We must only admit that we are face to face with a problem, whose solution in all probability must be attempted, and, we doubt not, completed by the astronomer." * Dr. Robert Brown, in a recent Memoir on the Miocene Beds of the Disco District (Trans. Geol. Soc. Glasg., vol. v., p. 55), has added considerably to our knowledge of these deposits. He describes the strata in detail, and gives lists of the plant and animal remains discovered by himself and others, and described by Professor Heer. Professor Nordenskjöld has likewise increased the data at our command (Transactions of the Swedish Academy, 1873); and still further evidence in favour of a warm climate having prevailed in Greenland during Miocene times has been obtained by the recent second German polar expedition. CHAPTER XIX. GEOLOGICAL TIME.-PROBABLE DATE OF THE GLACIAL EPOCH. Geological Time measurable from Astronomical Data.-M. Leverrier's Formulæ, Tables of Eccentricity for 3,000,000 Years in the Past and 1,000,000 Years in the Future.-How the Tables have been computed.-Why the Glacial Epoch is more recent than had been supposed.-Figures convey a very inadequate Conception of immense Duration.-Mode of representing a Million of Years.-Probable Date of the Glacial Epoch. If those great Secular variations of climate which we have been considering be indirectly the result of changes in the eccentricity of the earth's orbit, then we have a means of determining, at least so far as regards recent epochs, when these variations took place. If the glacial epoch be due to the causes assigned, we have a means of ascertaining, with tolerable accuracy, not merely the date of its commencement, but the length of its duration. M. Leverrier has not only determined the superior limit of the eccentricity of the earth's orbit, but has also given formulæ by means of which the extent of the eccentricity for any period, past or future, may be computed. A well-known astronomer and mathematician, who has specially investigated the subject, is of opinion that these formulæ give results which may be depended upon as approximately correct for four millions of years past and future. An eminent physicist has, however, expressed to me his doubts as to whether the results can be depended on for a period so enormous. M. Leverrier in his Memoir has given a table of the eccentricity for 100,000 years before and after 1800 A.D., computed for intervals of 10,000 years. This table, no doubt, embraces a period sufficiently great for ordinary astronomical purposes, but it is by far too limited to afford information in regard to geological epochs. The Seque Atanekerdli sentative. 53° N. F 59° or 61 ripening. and that c ture of A grew cou Profes "I th they are from th the view of ascertaining the probable date of s well as the character of the climate for al Ass Table I. was computed from M. Leve ⚫ows the eccentricity of the earth's orti the perihelion for 3,000,000 of years back. Cars 20 come, at periods 50,000 years apara ver the table it will be seen that there when the eccentricity rose to a very wbordinate maxima between. It will geach of those periods the eccentric 2e same uniform value, but rises and fa in the other two cases three tim back we have the eccentricity almost De begins to increase, and fifty thousa 21 2,600,000 years ago, it reach after this period it has diminishe P^«^ 18 present value. It then begins ander aty thousand years, namely aprozacões to almost the superior limi |