C.—GEOLOGY 69 
or belong to forms that are definitely marine, can their presence be 
regarded as satisfactory evidence of such conditions. 
There is another consideration that requires investigation, and in which 
fossil plants will assist the geologist. Huge thicknesses of strata of the 
sedimentary series must have been derived from land-areas, probably of 
fair elevation to allow the necessary gradient for streams. Were these 
lands clothed in vegetation? Examples of upland phases of plant-life 
are not always easily obtained, but, in association with volcanic action, | 
believe we have conditions that assist in preserving some record of such 
floras. During Lower Carboniferous times in Scotland, at any rate, the 
volcanic ashes enclose abundant remains of plant life; and, while we can 
say little about the actual amount of elevation of the areas concerned, the 
plants of the Pitys type, which were so common, with their short, thick, 
_ hairy phyllodes, show an adaptation to a drier environment than that 
occupied by the Lepidodendrea. ‘The proportion of wood in the axis of 
these Pitys trees also points to conditions where the individual could not 
depend as much on mechanical support from its neighbours as occurs in 
swamp growth; while the growth rings in the wood show, when they 
occur, responses to some rhythmic influence. These characters all point 
to Pitys as an upland type. The drifted plants of the ‘ roof’ nodules of 
the coal seams in England, also, probably furnish examples of an upland 
flora. 
There cannot be a shadow of doubt that the fossil plants of Carboni- 
ferous times have had, and still promise to have, important repercussions 
on our ideas of the geological conditions (including climatic conditions) 
of that age. 
PERMO-CARBONIFEROUS FLORAS. 
But while the Carboniferous flora in Europe and N. America continued 
into that of Upper Carboniferous times without any marked change of 
type, though, of course, with recognisable modifications and additions, 
there were great changes developed in other parts of the world. The 
Glossopteris flora has long been known, and its association with clearly 
marked glacial phenomena has given rise to much speculation. Beneath 
the beds bearing the Glossopteris flora are rocks containing a typical 
_ Lower Carboniferous suite of plants, i.e., when compared with beds of 
similar age in Europe and N. America. Exact correlation of the strata 
across the Tethys sea has not been effected, and, of recent years, there 
has been some tendency to draw attention to the rarer plants in the 
_ Glossopteris-Gangamopteris assemblages as illustrating connecting links 
between the flora in the southern hemisphere, or rather south of the 
Tethys, and that to the north. It has been suggested also that this flora 
must have lived in a cooler environment than that in which our Coal 
Measure plants flourished ; and that a shift of the South Pole to the 
Indian Ocean would give a distribution of the known localities, where the 
floras in question occur, such that the northern flora would occupy a more 
or less equatorial belt and the,Glossopteris flora one bordering upon polar 
regions. ‘Two considerations rather negative such an explanation: 
(a) there is no good ground for assuming that the Coal Measure flora was 
