GEOLOGY. 



RECENT PROGRESS OF GEOLOGY. 



THE following: is an abstract of an address given before the Geological 

 Section of the British Association, for 1858, at the opening session, by its 

 Chairman, Prof. W. Hopkins : 



The existence of mammalian life, in its earlier stages, on the surface of 

 our planet, the condition of its existence, and the period of its introduction, 

 have always furnished questions of the highest philosophical as well as 

 palseontological interest. You will be aware that some geologists regard 

 each new discovery of mammalian remains, in formations preceding the 

 older tertiaries, as a fresh indication of the probable existence of mammalia 

 in those earlier periods in which no positive proof of their existence has yet 

 been obtained; while others regard such discoveries only as leading us to an 

 ultimate limit, which will hereafter define a period of the introduction of 

 mammalia on the surface of the earth, long posterior to that of the first in- 

 troduction of animal life. Be this as it may, every new discovery of the 

 former existence of this highest class of animals must be a matter of great 

 geological interest. An important discovery of this kind has recently been 

 made, principally by the persevering exertions of Mr. Beckles, who has de- 

 tected, in the Purbeck beds, a considerable number of the remains of small 

 mammals. The whole of them are, I believe, in the hands of Professor 

 Owen, for the determination of their generic and specific characters ; but Dr. 

 Falconer seems already to have recognized among them seven or eight dis- 

 tinct genera, some of them marsupial, and others probably placental, of the 

 insectivorous order. 



The subject of the motion of glaciers is one of interest to geologists; for, 

 unless we understand the causes of such motion, it will be impossible for us 

 to assign to former glaciers their proper degree of efficiency in the transport 

 of erratic blocks, and to distinguish between the effects of glacial and of 

 floating ice, and those of powerful currents. An important step has recently 

 been made in this subject y the application of a discovery made by Mr. 

 Faraday, a few years ago, that if one lump of ice be laid upon another, the 

 contiguous surfaces being sufficiently smooth to insure perfect contact, the 

 two pieces, in a short time, will become firmly frozen together into one con- 

 tinuous transparent mass, although the temperature of the atmosphere in 

 which they are placed be many degrees above the freezing temperature. 

 Dr. Tyndall has the merit of applying this fact to the explanation of certain 

 glacial phenomena. There are two recognized ways in which the motion of 

 a glaicer takes place; one by the sliding of the whole glacial mass over the 

 valley in which it exists; and the other by the whole mass changing its 

 form in consequence of the pressure and tension to which it is subjected. 



