130 
POPULAR SCIENCE REVIEW. 
name being formed on the same principle as was adopted by 
Lyell in coming bis terms. Exception has been taken to this 
name of Professor Beyrich’s, but its very general adoption may 
be taken to prove that it supplied a want wbicb was beginning 
to be very generally felt. It is true tbat Lyell did not adopt 
tbis new term, but it may be safely asserted tbat, bad be lived 
to witness the recent advances in our knowledge of the deposits 
of tbis period, be would not have hesitated to accept the 
evidences in favour of its employment. Not only in Germany, 
Belgium, France, and England, but in the Alps and Eastern 
Europe, have beds of great thickness and importance, wbicb 
must be referred to this .division of the geological series, been 
discovered, and even in North America it has been shown that 
it is convenient to employ the term Oligocene to designate a 
division of the Tertiary series. 
It will be interesting to take a brief survey of the great 
series of deposits wbicb recent researches have led geologists tcj 
refer to the Oligocene period ; and in doing so we shall notice 
the evidence which they afford of the distribution of the land 
and sea, and the general physical features of Europe at the time 
of their deposition. 
It is in Eastern Europe that the Oligocene strata acquire 
their greatest normal thickness and development. In Transyl- 
vania and Hungary marine and brackish- water strata of this 
age are found, attaining a thickness of betwen .2000 and 3000 
feet. Dr. Anton Koch, of Klausenberg, has described the 
succession of the Oligocene strata in the neighbourhood of that 
town, where, resting upon beds containing the fauna of the 
Barton Clay, we find a thick series of deposits which can he 
referred to the Upper, Middle, and Lower Oligocene respec- 
tively. I have myself had the opportunity of studying the 
succession of these Transylvanian beds, and of noticing how the 
series of fossiliferous beds in that area can be paralleled with 
those of northern and western Europe. A similar succession 
has been made out in the Bihar Mountains and mother parts of 
Transylvania. As we proceed southward, however, towards the 
Turkish frontier, we find brackish-water and terrestrial condi- 
tions prevailing over the marine. This is well illustrated in the 
Tsil Valley, in the south of Transylvania, where at Petroseny 
a coal-bed, nearly ninety feet in thickness, is being worked in 
open pits and by means of adits. This great coal-seam and 
others of lesser thickness are intercalated in a series of strata, 
which contain a characteristic Oligocene fauna, the strata in 
question having been preserved from denudation through being 
thrown into a synclinal fold. 
In the country round Buda-Pest the Oligocene strata have 
been carefully studied by Dr. Szabo, and their fossils have been 
