92 PRINCIPLES OF STRATIGRAPHY 



have moved about 3° from its original position. If, however, the 

 earth is plastic, as seems to be the case to a certain degree, so that it 

 could readjust itself to the form of equilibrium, then there is a pos- 

 sibility of a cumulative effect, and the pole may have wandered 10° 

 or 15° from its original position. This subject is more fully dis- 

 cussed in Chapter XXIII. 



ORIGIN OF THE ATMOSPHERE. 



According to the nebular hypothesis of earth origin, the atmos- 

 phere is merely the residuum of uncombined gases which were left 

 behind when the globe assumed its solid form. To this are added 

 various supplies, chief among which is the carbon dioxide from 

 volcanic eruptions, the decay of organic matter, and the burning of 

 coal. The Planetesimal hypothesis of Chamberlin, on the other 

 liand, considering the earth as made up of aggregations of small 

 solid bodies coming from space, derives the atmosphere from the 

 small quantities of entangled or occluded atmospheric matter 

 brought by these planetesimals. The pressure of the accumulating 

 cold matter eventually produced sufficient internal heat to expel 

 these gases. If the conception of an internal gaseous centrosphere 

 can be entertained, the possibilities of addition to the atmosphere 

 are greatly enhanced. 



BIBLIOGRAPHY II. 



1. ANDERSSON, J. G. 1910. Die Veranderungen des Klimas seit dem 



Maximum der letzten Eiszeit. Papers by Gunnar Andersson (summary 

 also for North Italy, Greece), F. Wahnschaffe (Germany), G. van Baren 

 (Netherlands), A. Rutot (Belgium), G. W. Lamplugh (Great Britain), 

 H. Brockmann-Jerosch (Switzerland), T. Taramelli (Italy), E. Bruckner 

 and A. v. Hayek (Austria), L. de Loczy, E. de Cholnoky, T. Kormos, P. 

 Treitz, K. Gorjanovic-Kramberger (Hungary), G. Murgoci (Rumania), 

 G. I. Tanfiljef (Russia), H. Lindberg (Finland), R. Sernander, Gunnar 

 Andersson, G. de Geer (Sweden), V. Nordmann and C. G. Joh. Petersen 

 (Denmark), Jens Holmboe, P. A. Ojen (Norway), G. Bardarson (Ice- 

 land), Wm. C. Alden, W. H. Dall, F. H. Knowlton, O. P. Hay (United 

 States), G. F. Matthew, J. A. Dresser, Frank D. Adams, A. P. Coleman, 

 J. B. Tyrrell, R. W. Brock, R. G. McConnell (Canada), Ad. S. Jensen, 

 Poul Harder, Gunnar Andersson (North Polar Region), W. F. Hume 

 (Egypt), M. Blanckenhorn (Syria, Palestine and Egypt), Sven Hedin 

 (Persia), G. E. Pilgrim (India), A. W. Rogers (Cape Colony), R. v. 

 Lendenfeld (Australia and New Zealand), C. Skottsberg (Patagonia and 

 Terra del Fuego), R. Hagg (Southern South America), E. Philippi 

 (South Polar Region). Stockholm. 



2. ARRHENIUS, SVANTE. 1896. On the Influence of Carbonic Acid in 



the Air upon the Temperature of the Ground. Philosophical Magazine, 

 Decade V, Vol. XLI, pp. 237-276. 



