A02= HT, W. TURNER 
be found in the conglomerates of the Knoxville formation. 
Such conglomerates were observed at Knoxville, in Napa county. 
When making a geological map of the Knoxville quicksilver dis- 
trict for Dr. Becker, I collected some pebbles from these con- 
glomerates, and later published’ a few notes concerning them. 
As the characteristic fossil of the Knoxville formation (Aucella) 
occurs in this conglomerate, there can be no doubt concerning 
its age. The pebbles are of various porphyries, including soda- 
syenite porphyry and augitic porphyries and fine cherty pebbles, 
indistinguishable from the rocks called phthanites by Becker, 
radiolarian cherts by Lawson, and Jaspers by Whitney and Fair- 
banks. A thorough investigation of these conglomerates will, 
perhaps, bring to light pebbles of some of these schists, the ori- 
gin of which is ascribed to contact metamorphism and thus 
make certain their pre-Knoxville age. This being established, 
it would at least be certain that these rocks, if formed by con- 
tact metamorphism, were not formed by the serpentines which 
are found intruded into the Knoxville formation. 
To the southeast of Coulterville,?in Mariposa county, and at 
other points, there are dikes of soda-feldspar, which are fre- 
quently intruded along the contact of serpentine masses with 
other rocks: — These Soda-syenite ‘dikes, where altered, otten 
contain blue amphibole in varying amount. Some of this may 
be primary, but part of it is secondary, The formation of glau- 
cophane-schists (soda-amphibole) from crushed rocks contain- 
ing much albite (soda-feldspar) seems quite possible. This is 
heightened by the finding by Ransome of white bunches com- 
posed of albite, in association with the glaucophane-schists on 
Angel Island. The suggestion of such an origin for the glauco- 
phane-schists of the Coast Ranges should not, however, be taken 
too seriously. 
Fossils being rare in the Golden Gate formation, all locali- 
ties where remains have been found are worthy of note. About . 
one mile (1.6 klms.) northeast of the summit of the north peak 
t Am. Geol., Vol. XI, May 1893, p. 316. 
27th Anns Ne pt Uso. Gans.) Pts 720N, 
