Vice-President’s Address. 205 
This division contains all the workable coals of Coal- 
Measure age that occur in Scotland. 
Many writers on Scottish geology refer to this series as the 
Upper Coal-Measures in distinction to the coals worked in 
the Carboniferous Limestone Series, which they call the 
Lower Coal-Measures, Lower Series, or Lower Coals. But 
the so-called Lower Coal-Measures or Series are not Coal- 
Measures at all, and the loose application of the term “ Coal- 
Measures” or “Coal Series” to all strata containing workable 
coal seams, has done much to create misconception as to the 
true position of the fossils derived from the coals of the 
Carboniferous Limestone Series or “ Edge Coal” Series.” 
MILLSTONE GRIT SERIES. 
Although many geologists consider that there is no very 
definite stratigraphical line of separation between the Mill- 
stone Grit and the underlying Carboniferous Limestone 
Series, an enormous interval of time must have elapsed 
between the formation of these two series—an interval, 
the existence of which is proved by a complete change in 
the flora of the Millstone Grit from that occurring in the 
underlying Carboniferous Limestone Series. 
It is well known that any change in the form of life has 
been a gradual and slow process, and that no sudden breaks 
occur in the chain of organic existence, and that any change 
undergone by the flora and fauna of bygone ages represents a 
longer or shorter period of time-—a period the duration of 
which is measured by the changes produced; and its presence 
is as clearly proved by these changes as if it had been repre- 
sented by the formation of beds of solid rock.? 
1 Leaving out of account the Canonbie Coal Field, about whose geological 
position there remains some doubt. 
2 Suchterms as the following are frequently met with in writings on Scottish 
geology :—‘‘ Lower Coals and Ironstones,” ‘‘ Upper Coals and Ironstones,” 
“* Upper or True Coal-Measures,” ‘‘ Scottish Upper Coal-Measures.” To one 
unfamiliar with the geology of Scottish Carboniferous rocks, such terms are 
very confusing. 
5 Jt is known that precisely the same lithological type of rocks is found 
in the upper part of the Yoredale Rocks as occurs in the Millstone Grit itself. 
We may infer from this that similar conditions prevaried both before and 
after this paleontological break, 
