300 It. D. Oldham — Probable Changes of Latitude. 



in North America at about the same horizon. It is, however, at 

 present impracticable for me to follow up this question for want of 

 access to books of reference ; but this is of comparatively minor 

 importance, as my purpose has merely been to show that there have 

 been glacial epochs comparable to that of the Post-Tertiary period ; 

 and having shown that such a glacial epoch did at one time affect 

 a large portion of the Earth's surface, it becomes easy to acknowledge 

 that similar periods of cold have occurred before and since, and that 

 we must not attempt to ascribe every occurrence of Glacial beds of 

 Tertiary or Pre-Tertiary age to some merely local cause. And 

 having acknowledged this, we at once obtain what was wanted, a 

 check on the palaeontological timepiece, a time-signal on the chrono- 

 graph of the world. 



Note. — A month ago I would have appealed, as proof positive of 

 the contentions stated above, to the discovery in the Salt Range of 

 the Punjab of marine fossils identical with those of the Australian 

 Carboniferous beds. These are derived from beds which exhibit 

 ample proofs of glacial action, and were on that ground assumed 

 by Dr. Waagen to be of the same age as the Talchirs, which he 

 agreed with most of the members of the Geological Survey in 

 regarding as of Palaeozoic age. The pebbles in which the fossils 

 were found might in hand-specimens be taken for concretionary 

 nodules, and an imperfect description of their mode of occurrence 

 would support this idea ; moreover the coincidence of the fauna and 

 physical conditions with those of the Australian beds is very striking. 

 There was every temptation for me to accept Dr. Waagen's con- 

 clusions, but a careful examination of the beds, and of the mode 

 of occurrence of the fossils, has convinced me that this is a mere 

 coincidence, and that the fossils, which occur as transported pebbles, 

 can consequently be of no use in determining the homotaxis of the 

 beds from which they are derived. The stratigraphical relations 

 of these beds are such as to associate them with the Nummulitics ; 

 and as boulder beds, presumably of glacial origin, have been re- 

 corded by Mr. Lydekker as conformably underlying the Nummulitics 

 of Ladak, there is no difficulty in finding a horizon to which the 

 beds can be referred. 



III. — Essays on Speculative Geology. 



2. — Pbobable Changes of Latitude. 



By R. D. Oldham, A.R.S.M. etc. 



Part I. — Glacial Periods in Low Latitudes. 



IN my last essay I had occasion to refer to the former existence of 

 icebergs in localities which now lie in latitudes lower than those 

 in which glacial action is known to have reached, even during the 

 last Glacial period. But, surprising as it may be to find evidence of 

 glacial action within a few degrees of, and, as in the case of the 

 Bowen Biver Coal-field, a few degrees within, the tropics, this sinks 

 into insignificance in the face of the evidences of repeated Glacial 

 periods that may be found in India, and especially in the Himalayas. 



