292 Proceedings of the Royal Physical Society. 
Yorkshire, near Bristol, at various localities in Ireland, at 
Copeth (“ Cockburnspath”) on the Berwickshire coast, and, 
lastly, in the city of Edinburgh. In other places it appears 
to me that there is evidence of a certain amount of uncon- 
formity between the two formations—not on paleontological 
grounds alone, but also on physical. The Lower Carboniferous 
Rocks of Cumberland, for example, of East Fife, probably also 
of the Pentlands, appear to me to lie trangressively across the 
denuded ends of the older rocks, including the Upper Old 
Red, in a manner suggestive of something more than contem- 
poraneous erosion. Messrs Lapworth and Watts (“ Geology 
of South Shropshire,” p. 331) refer to facts of much the same 
kind in that district. Although the unconformity may not 
appear to be great, it certainly coincides with the final dis- 
appearance of the very remarkable groups of fishes which 
characterise the Old Red. Personally, I doubt whether the 
geographical change from that of desert conditions and inland 
lakes to marine conditions affords altogether a satisfactory 
explanation of the phenomena. Lapse of time is a factor of 
equal importance, and all the evidence to the contrary in 
this particular case has completely broken down with 
advance of knowledge. 
From the Upper Old Red Sandstone, petrographically con- 
sidered, we can draw no conclusions of any value respecting 
the time implied in the formation of these rocks. But the 
researches of Dr Traquair have made known to us the fact 
that paleontological zones exist in the Upper Old Red as 
in other formations. It is difficult to see how this could 
arise unless the formation of the rocks in question occupied 
a very long time. 
In the absence of definite data, I am reluctantly com- 
pelled to omit this from the calculation. But, as will 
be seen presently, the marine Devonian of the Continent 
is probably contemporaneous with not only the lower parts 
of the Old Red series, but with the Upper Old Red as well, 
so that we shall count it in another connection. 
1 «Extinct Vertebrata of the Moray Firth Area,” in Harvie-Brown and 
Buckley’s ‘‘ Vertebrate Fauna of the Moray Basin,” vol. ii. Edinburgh, 
1896. 
