398 Scientific Intelligence. 
When I wrote those articles I was not ignorant that swrmises 
had been recorded before, that “ possibly” the rocks in question 
might be in part Carboniferous, but the articles in question dealt 
rather with what the Geo ological Survey had proved than with 
what — had guesse 
admit that oaneaae had been copiously put forth in 
Prof. Blake? $s report, and upon a variety of questions. rmi- 
ses that the Sierra limestones are “ possibly” Carboniferous, (the 
si 
e Devonian,”—that they ma “ Silurian,’—that they were 
“ probably impregnated hoe it [gold] after the Miocene period,” 
—that the coast Ran anges had been covered with the sea until 
“Post Tertiary times,’—and so on through a suggestive list of 
surmises, a few of which have been sustified by later investigation, 
pee the most of which however are now known to be unfoun 
A paragraph in this recent article appears to indicate that he 
as much underrates the value of facts as he overrates the value of 
sibilities, Respecting the age of the very rocks in = 
the surmise of which age “was a bold step in advance,”) he sa 
{p. 266) “that as regards the portion of the gold-belt under con- 
sideration it is as yeta matter of opinion, not of demonstration.” 
it has not been rs at all, as the language implies, then 
it is untrue, to illustrate that the last is his meaning, 
and td make it ake probable ; e discovery of other 
h 
at Bass Rancho and STs srs has a additional evi- 
dence, and yet Mr. Brewer very justly does not positively assert 
the Carboniferous age of this belt pre ere &e. Here again 
f. Blake values facts too lightly as compared with the surmises 
which — the — and in but “partially citing para- 
graphs from report,” he curiously omits to mention that I had 
eited another -ioeality of Carboniferous fossils m any miles farther 
“southward” where the fossils are found in at least two beds or 
localities, bacorstar ea by auriferous ane and both enclosed in those 
slates. ality is mentioned in the paragraph whic h he 
arial ite be peotniecs to eall attention to some —— peculiari- 
ties of this recent article. I have published some of the more 
“importa ; ual discoveries bearing 
on the question. I did not exhaust the list, it could have been 
extended, but it was considered sufficient for the purposes 
