AMERICAN 
JOURNAL OF SCIENCE AND ARTS. 
[SECOND SERIES.] 
Art. L—Thirty Years Retrospect of the progress in our knowledge 
of the Geology of the Older Rocks—being an Address to the 
Geological Section of the British Association at Manchester, 
September 5, 1861;° by Sir Ropertck Impey MuRcHISON, 
D.C.L., LL.D., F.R.S., Director General of the Geological Sur- 
vey of the United Kingdom, President.* 
AttHoucGu I have had the honor of presiding over the Geol- 
ogists of the British Association at several previous meetings 
since our first gathering at York, now thirty years ago, I have 
never been called upon to open the business of this section with 
an address; this custom having been introduced since I last 
occupied the geological chair at Glasgow, in 1855. 
The addresses of my immediate predecessors, and the last an- 
niversary discourse of the President of the Geological Society 
of London, have embraced so much of the recent progress of our 
science in many branches, that it would be superfluous on my 
ar ee again over many topics which have been already we 
treated. wes 
Thus, it is needless that I should occupy your time by allu- 
ding to the engrossing subject of the most recent natural opera- 
tions with which the geologist has to deal, and which connect 
his labors with those of the ethnologist. On this head I will 
I am as complete a believer in the commixture in that ancient 
* Communicated to this Journal by Sir R. L Murchison. 
Am. Jour. Sc1.—Sreconp Series, Vou. XXXII, No, 97.—Jan., 1862, 
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