Smithsonian Report, 1899. — Holmes. 



Plate I. 



1.— Section showing conditions in early Tertiary times. A, Auriferous slates; a, b, stream bed.';. 



2. — Conditions at close of great gravel-forming period and before volcanic activitv began. 

 A, Auriferous slates; o, b, river beds clogged with auriferous gravels. 



3.— Conditions at close of volcanic period: valleys filled up and mountains buried with eruptive 

 formations. A, Auriferous slates; a, b, c, river channels. 



■1.— Conditions to-day. Rivers in channels 2,000 feet deep. Remnants of volcanic deposits and 

 old river gravels capping mountain summits, e, e. Old profiles showm by dotted lines. 



Transverse Sections of River Channels, auriferous Gravel Region, representing 

 THE Profiles as they are supposed to have appeared at four widely separated 

 Periods. 



