A. W. Chase—Gravel Deposit of Gold Bluffs. 379 
as hard as sodium, a metal as soft as wax. It does not seem 
possible to accept the statement that a revolving steel plunger 
will penetrate a quarter of an inch into a diamond, in less time 
than, all other things being equal, it will penetrate an inch and 
a half into lead. 
Arr. XXXIIL—The Auriferous Gravel Deposit of Gold Bluffs ; 
by A. W. Cuasg, Assistant U. S. Coast Survey. 
(Read before the California Academy of Sciences, Jan. 5th, 1874.) 
miles south of the ems banks and deposits of gravel appear, 
the blufis are absolutely vertical and in some instances over- 
‘anging. At low water there is a narrow beach, ul 
tide is full the sea washes directly against the base of the cliffs: 
the beach is then impassable. 
