1848.] HAMILTON ON THE AGATE QUARRIES OF OBERSTEIN. 209 
patches of the red sandstone, lying far from the general mass of this 
rock, proving that it has at one time covered up the mass of the 
greywacke to a considerably greater extent, no intermediate geologi- 
cal event can be shown to have occurred. This circumstance leaves 
the period of the last depression of the land, and the deposition of 
the diluvium upon it, in a great measure undecided. 
JANUARY 19, 1848. 
The following communication was read :— 
On the Agate Quarries of OBERSTEIN. By W. J. Hamiuton, Ksq., 
Sec. G.S. 
In the autumn of 1844 I visited the agate quarries of Oberstein, and 
as I believe that no notice of them has been yet offered to the Geo- 
logical Society, I trust that the followmg observations, however slight, 
will not be altogether uninteresting. Indeed it is rather surprising, 
considering the interest attached to the origin and formation of agates 
and of other siliceous nodular deposits, and the different views which 
have been advanced on the subject, and knowing as we do that these 
quarries have been visited from time to time by some of our most 
eminent geologists, that no account whatever has yet been given of 
this locality in any of the publications of the Society. 
I allude more particularly to some remarks and opinions contained 
in a paper by Mr. Bowerbank, read before the Society on the 19th 
of May, 1841*, in which he states that he has discovered the exist- 
ence of remains of sponges in moss-agates from Oberstein, and from 
which he seems to infer that all agates, as well as chalk-flints and 
greensand cherts, have originated from sponges and other similar 
organic bodies. Without stopping however to inquire whether the 
substances which Mr. Bowerbank calls moss-agates are in any degree 
essentially different from the agates and other siliceous substances 
which I found at Oberstem and in the neighbourhood, I shall endea- 
vour to show in the following remarks that the rocks in which the 
real agates of Oberstein are found are igneous rocks, and that the im- 
bedded masses owe their origin to causes which, to all appearance, 
preclude the possibility of their contaming any remains of organic 
bodies. 
The little village of Oberstein is situated about thirty miles from 
Kreuznach, up the valléy of the Nahe, in a nearly west-by-north 
direction from the latter place, on the road from Bingen to Saar- 
bruck. Here is the junction of the coarse red conglomerate beds, 
which form the basis of the sedimentary formations of this district, 
with the underlying green amygdaloidal trap rocks. This conglome- 
rate may be traced several miles down the valley, overlying and lap- 
ping round the various protruding masses of trap and porphyry ; the 
imbedded pebbles appeared to consist exclusively of quartz rock, grits, 
greywacke and porphyries of various kinds. 
* Proceedings of the Geological Society, vol. iii. p. 431. 
VOL. IV.— PART I. R 
