438 On a Phaenomenon 
~ The system of Dr. Hutton, and also of Mr. Playfair in 
his [llustrations of this system, is; that the mineral veins 
have been produced by substances proceeding from below 
the strata, and injected when softened by heat, in the frac- 
tures of the strata, in the same manner that Mr. Playfair 
supposed that the vetas of St. Michael’s Mount had been 
produced. 
I was too well acquainted with mineral veins, not to see 
the error of that system of Dr. Hutton; having gone down 
the greatest and deepest mines in the mountains of the 
Hartz, with the best cuide for such observations, Baron de 
Rheden, the chief director of these mines; and 1. have 
published these observations since 1780. - Thus, before this 
Jast journey in Germany, we had coincided in the same 
opinion, the celebrated M. Werner of Freyberg in Saxony 
and myself (without having yet any knowledge of each 
other), that mineral veins had been successively filled by de- 
posits of chemical precipitations on the sides of the fissures 
in the strata, from the liquid of the former sea. 
This -coincidence made me desirous of a personal ac- 
quaintance with M. Wemer: therefore, being arrived at 
Dresden, I wrote to him to inquire whether he was at 
Freyberg, and could help me in my wish to study that ce- 
brated mineral country. Instead of answering, M. Werner 
came to Dresden, with the intention to be himself my 
conductor. 
This journey begins at p. 435 of the Ist volume. Un- 
der such auspices, every part of our observations is inter- 
esting to geology, not only with respect to the nature of 
mineral veins, but on Mr. Allan’s principal subject, an- 
nounced in these words: Remarks on the Transition Rocks 
of Werner. The observations we made in that journey, in 
which M. Werner himself pointed out to me disturbances, 
dislocations, changes of original relative position of the 
different kinds of strata, entirely agreed with the descrip- 
tions which I] had already published of these phenomena, 
as may. be seen in the account of this journey; but I shall 
confine myself to the object of mineral veins, which is par- 
ticularly described in pp. 446 and 4473; of which I shall 
give only extracts, 
*¢ On this subject M. Werner supplied me with an im- 
mediate proof, that the veins, within each particular di- 
strict, are not of the same date: some of the veins here 
had already been filled with their gangue, when fresh cata- 
strophes produced new fissures which passed across the for- 
mer; yet still at so early a period, that the last veins wer¢ 
filled 
