3G8 THE GEOLOGIST. 
poraneous — as formations acted upon by processes affecting the 
whole earth's surface at the same time. If our supposition be cor- 
rect, they are only the everywhere tolerably analog-ous consequences 
of local eruption, which may have been very far separated from each 
other by time. The baryte-veins at Freiberg, in the Thiiringer 
Wald, and in the south of France, may belong to very different 
geological epochs ; they are to be considered, wherever they are 
found, as representing the same stadium of local eruptive activity. 
The same holds good for the regular succession of minerals found in 
veins, druses, and amygdaloids ; the same series may have repeated 
itself at very different times. The stages of this series cannot, 
therefore, be used generally to define age like those of the 
sedimentary formations ; they intimate only the relative age of the 
isolated local process of formation. 
We shall now endeavour to apply these general theories to the 
more essential phenomena of the Freiberg ore-veins. 
( To be eontmued). 
NOTES AND QUERIES. 
Field-Meetings of the Geologists' Association. — Sir, — lu the last 
number of your excellent magazine a letter appeared, in wliicli a suggestion 
was brouglit forward that it would be well for the Geologists' Association to 
institute occasional field-meetings. Such a course would be, without doubt, 
exceccUngly advantageous, as it would tend to make the members better 
acquainted with each other, and to increase their interest in the science. Tor 
my own part I should be very glad to see the plan adopted, knowing that a 
lecture giving at a natural section and on the fossils in situ is far more valuable 
and instructive than one illustrated by the most expensive diagrams. The 
connnittee of the Geologists' Association, however, feel they are not in a posi- 
tion to carry out the proposal dtiring the present year ; but tliey hope, and 
they have deputed me to make tliis statement, tliat during the next they shall 
be able to invite the members to a geological ramble, and to spend a summer's- 
day botli pleasantly and profitably. — I am, Sir, youi's faithfully, Thomas 
Wiltshire. 
Artificial Origin of Rock-Basins. — In your magazine, valuable on 
account of the popular style in which it treats our beautiful science, I was last 
montli very pleased to read tiie remarks of Mr. Ru])ert Jones on the weathering 
of granite, and especially that portion of them referring to the rock-basins of 
Dartmoor. Having been born and brouglit up in the neighbourhood of this 
district, I liappen to know the rock-basins, logging-stones, and chcese-shapcd 
granite-rocks well; and it is because I am obliged to take exception to the 
remarks of Mr. Ku()ert Jones on the formation of the " rock-basins," that I 
