ial ° <a <9 F ox 
OEP ui ‘ é 2 
¥ i ae % i : ies. Sef aS 
’ ¢ ey 
™ Ly 
FY Alger on Crystallized Gold joi California. 101 
the lake eal the loose movable materials consist of the same 
_,* cation in the te bei structure of ne country. But if, on the 
"i contrary, we suppose the lake to have removed the barrier, there 
» 1s no cause left for its accumulation, and the changes in the com- 
-parative level of the main land and the terraces remain equally 
*amaceounted for 
| -:* Indeed, the terraces are so unequal in their absolute level when:- 
“compared to each other, that a gradual #ubsidence af the lake 
removing a barrier of loose materials at dee could pever ex- 
plain their irregularity. But if we suppose that the i it 
dykes which cross, in all directiong the rocks whiclf form the 
_ Shores of the lake, have at various intervals lifted up these shores, 
_ We have at the same time a cause fot the change of the relative 
level between the terraces and the lake, and also for the change 
of its absolute level, as it removed farger and larger portions of 
_ Materials accumulated at its eastern extremit 
-_ That these dikes have produced such changes will not be 
doubted by any one who may study the phenomena described in 
the following chapter respecting the origin of the present outlines 
of the lakes, as produced by the intersection of all the dikes 
we the metamorphic and plutonic rocks of the northern 
ores. 
We should therefore conclude that, as there has been a general 
o 
<4 
o 
° 
tear) 
[ eal 
> 
oO 
o 
cal 
Oo 
~ 
ia) 
Qu. 
= 
wn 
v2) 
o 
_~2 
9 
w 
i] 
‘= 
[om 
a 
oO 
| 
Be 
ie*] 
- 
> 
ia) 
So 
ie) 
39 
ee 
ia) 
= 
is) 
oS 
=) 
3 
ia) 
=| 
is] 
would only corroborate the induction derived from more general 
geological facts 
Arr. XIV. oy te Gold Md meer = by 
s Aucer, Bosto 
I wave lately had an opportunity of examining some gm x 
California gold, which have afforbled s specimens worthy of e 
be notice. Those which I purpose to describe in this Saver ; 
ined from the collections brought home by Mr. George E. 
Tyler, of this city, and Mr. H. B. Platt, of New York. They 
consist of well characterized octahedral crystals, simple and modi- 
» the surfaces of which have been but slightly disfigured by 
* Read, in part, before the Boston Society of Natural History, April, 1850. 
