TRANSACTIONS OF SECTION C. 509 
Society of London in May last ;! other notices on the subject have been published 
in the papers of the Archxological Institute of America. 
The oldest rocks of the Troad are the crystalline schists with limestones which 
form the Ida range (5,750 feet), and which also appear in smaller and lower areas 
elsewhere. From the limestone-beds of this series, on the flanks of Ida, most of the 
springs arise which ave the sources of the chief rivers of the Troad. The age of 
this series is unknown; it is probably Archean. 
Resting unconformably upon these beds, and in part composed of them, is a 
newer series of partially altered rocks, which may range in age from Paleozoic to 
Eocene ; but this series requires more examination. 
The Upper Tertiaries are sharply marked off from these older rocks ; they occur 
in two separate areas. The older series is marine; it is found mainly along the 
western and north-western part of the Troad. These beds belong to the Sarmatian 
stage—Upper Miocene. The newer Tertiary series is composed of fresh-water beds, 
Upper Miocene or Lower Pliocene, occurring mainly in the interior of the country, 
and especially along the plane of the Mendere. 
The oldest igneous rock is granite, which invades and alters the oldest 
(? Archean) crystalline rocks. Dykes of quartz-porphyry intersect this. Quartz- 
diorite invades the second, or partially crystalline, sedimentary series. 
Of the newer igneous rocks andesites and liparites are the oldest ; where they 
can be studied together the latter is the later of the two. Of later date are basalts 
and nepheline basalts. 
5. On the Causes of Change of Climature during Long Periods of Time, and 
of Coincident Changes of Fauna and Flora. By Joun Guyv.? 
The object is to show that, as the elevation of mountain-ranges is the principal 
cause of cold, so the converse is true—namely, that their subsidence, in long periods 
of time, is the cause of warm temperatures. 
Without attempting to account for the origin of the inequalities of the earth’s 
surface, or to throw any light upon the cause of the upheaval of the land, the author 
endeayours to prove the reality of his proposition, and commences with the Carboni- 
ferous period. 
There is evidence of a normal and quiescent state during which coal was de- 
posited ; not an instance can be adduced of an ice-scratched boulder, but a mild and 
subtropical climate appears to have prevailed. 
Passing to the Permian, the change both of fauna and flora appears to be coin- 
cident with that of the level of the land. A great and general disturbance took 
place, and glaciated and striated rocks prove the reality of a Glacial period, as ob- 
served by Professor Ramsay. 
From that era, and throughout the oolitic series, a gradual and general levelling 
occurred, and there is no appearance of scratched boulders. Marsupial animals 
attest a subtropical surface of the land, and saurians indicate the like condition of 
the sea. Throughout the Purbeck beds the marsupial form is continued, and in the 
Dirt-bed of the Isle of Portland the Zamia represents a tropical flora. 
The same remarks may be made respecting the prevalence of a warm climate 
during the cretaceous series. The chalk was laid down in a warm sea horizontally, 
and its elevation into its present inclined and irregular position was accompanied 
with a lowering of the climate and concurrent change of fauna and flora. 
The Eocene and still more the Miocene formations exhibit very gradually but 
decidedly the effect of change of level and disturbance of the strata, but no striated 
boulders that the writer is aware of, nor any indication of ice-action have been 
discovered in them. 
But the effect of such changes becomes more obvious in Pliocene times; and in 
no part of the world are there the like facilities for observation as in the eastern 
counties of England. There, from the continuity of the strata, the relations of 
cause and effect are minutely traceable, and it may be clearly seen how the varia- 
1 Quart. Journ. Geol. Soc. vol. xxix. p. 627, with Geol. Map ; Appendix by W. Topley. 
2 Published in extenso Geol. Mag. Dec. iii. vol. i. p. 73. 
