CARBONIFEROUS VOLCANIC ROCKS OF THE FIRTH OF FORTH BASIN. 439 
shall have occasion elsewhere to refer to these various papers, it will be 
sufficient at present to point out that the igneous rocks of the Edinburgh 
district have afforded materials for some well-known researches in theoretical 
and structural geology, and to allude to a few of the more important descrip- 
tions of them. These rocks formed the subject of some of Hutron’s early 
observations, and furnished him with the facts from which he established the 
igneous origin of ‘whinstone.”* They supplied PLayrarr with numerous 
apt illustrations in support of HuTron’s views, and he seems to have made 
himself thoroughly familiar with them.t In the hands of Sir James Hatt they 
formed the groundwork of those remarkable experiments on the fusion of 
whinstone which may be said to have laid the foundation of experimental 
geology.{ In the controversies of the Neptunian and Plutonian schools these 
rocks were frequently appealed to by each side in confirmation of their respec- 
tive dogmas. The appointment in 1804 of JAmeEson to the Chair of Natural 
History in the Edinburgh University gave increased impetus to the study of 
the igneous rocks of this region. Though he did not himself publish much 
regarding them, we know that he was constantly in the habit of conducting 
-his class to the hills, ravines, and quarries of the neighbourhood, and that the 
views which he taught were imbibed and extended by his pupils.§ Among 
the early writers the names of ALLAN,|| Townson,{ and Lord GREENOCK,** 
deserve especial mention. 
The first broad general sketch of the igneous rocks of the basin of the Forth 
was that given by Hay CunnincHam in his valuable Essay on the Geology 
of the Lothians.tt He separates these rocks into two series, the Felspathic, 
including porphyry and clinkstone, and the Augitic or Trap rocks. To these 
he adds Trap-tufa, and considers it identical in origin with modern volcanic 
tuff. It is the eruptive character of the igneous rocks on which he specially 
dwells, showing by numerous sections the effects which the protrusion of the 
molten masses have had upon the surrounding rocks. He does not attempt to 
separate the intrusive from the interbedded sheets, nor to form a chronological 
arrangement of the whole. 
Still more important was the sketch given by Mactaren, in his classic 
“Geology of Fife and the Lothians,” tf} a work far in advance of its time. The 
* Hutton’s “ Theory of the Earth,” vol. i. p. 155, e¢ seq. 
7 Playfair’s “ Illustrations of the Huttonian Theory,” § 255, et seq. 
Tt See “Trans. Roy. Soc. Edin.” (1805), vol. v. p. 43. 
§ See “Mem. Wern. Soc.” ii. 178, 618; iii. 225; “Edin. Phil. Journ.” i. 138, 352 ; xv. 386. 
|| “Trans, Roy. Soc. Edin.” (1811), vi. p. 405. 
{ “Tracts and Observations in Natural History and Physiology,” 8vo, Lond. 1799. 
** “Trans, Roy. Soc. Edin.” (1833), xiii. p. 39, 107. 
Tt “Mem. Wern. Soc.” vii. p. 1. Published separately, 1838. 
tf Small 8vo, Edin. 1838, first partly published as articles in the Scotsman newspaper. 
