Br. John Evans's Address to Section C. 419 



appear to point to a great want of homogeneity in tlie interior of our 

 planet, and might suggest a possible cause for some disturbance of 

 equilibrium. 



I have mentioned Professor Haughton among those who, from 

 mathematical considerations, have arrived at the conclusion that a 

 geographical change in the position of the axis of rotation of the 

 earth is not only possible, but probable. In a recent paper, how- 

 ever, he has maintained, notwithstanding this possibility or pro- 

 bability, we can demonstrate that the pole has not sensibly changed 

 its position during geological periods. He arrives at this con- 

 clusion by pointing out that in the Parry Islands, Alaska and 

 Spitzbergen, there are Triassic and Jurassic deposits of much the 

 same tropical character, and then by a geometrical method fixing 

 the North Pole somewhere near Pekin, and the south pole in 

 Patagonia, within seven hundred miles of a spot where Jurassic 

 ammonites occur, shows that such a theory is untenable. In the 

 same way he fixes the pole in Miocene times near Yakutsk, within 

 eight hundred miles of certain Miocene Coal-beds of the Japanese 

 islands. These objections are at first sight startling, but I think it 

 will be found that if, instead of drawing great circles through certain 

 points, we regard those points as merely isolated localities in a belt 

 of considerable width, there is no need of fixing the pole of either 

 the Jurassic or the Miocene period with that amount of nicety with 

 which Professor Haughton has ascertained its position. The belt 

 may indeed be made to contain the very places on which the 

 objection is founded. Still the method proposed is a good one, and 

 I hope that as our knowledge of foreign geology extends it may be 

 still further pursued. There is, however, one farther consideration 

 to be urged, and that is as to the safety of regarding all deposits of 

 one geological period as contemporaneous in time. Although an 

 almost identical flora may be discovered in two widely-separated 

 beds, it appears to me that chronologically they are more probably 

 of different ages than absolutely contemporaneous ; and, inasmuch 

 as the duration of the Miocene period must have been enormous, 

 there would be time — if once we assume a wandering of the poles — 

 for such wandering to have been considerable between the beginning 

 and end of the period. 



I must not, however, detain you longer upon this phase of 

 geological speculation, but will advert to a subject of more practical 

 interest, the discovery of Palseozoic rocks under London. So 

 long ago as 1856 the Kentish Town boring had shown that im- 

 mediately below the Gault red and variegated sandstones and clays 

 occurred, which Professor Prestwich regarded as probably of Old 

 Eed or Devonian age. The boring of Messrs. Meux & Co. has 

 now shown that under Tottenham Court Eoad, at a depth of little 

 more than nine hundred feet from the surface, there are true 

 Devonian beds, with characteristic fossils, and that Mr. Godwin- 

 Austen's prophecy of the existence of PalEsozoic rocks at an acces- 

 sible depth under London has proved true. Professor Prestwich, 

 from a consideration of the French and Belgian coal-fields, inclines 



