The Rocks of the John Day Valley. 159 



themselves, and the foundations on which 

 they stand, are here found to be sedimentary 

 rock, wonderfully filled with the abundant 

 records of former animal and vegetable life. 

 Oldest of all in sight is the old ocean bed of 

 the Cretaceous period, with its teeming thou- 

 sands of marine shells, as perfect to-day in 

 their rocky bed as those of our recent sea 

 shores, their cavities often filled with calca- 

 reous spar or chalcedony as if to compensate 

 for the loss of their own proper marine hues. 

 Next in ascending order come the fresh-water 

 deposits of the earlier T ertiaries, so full of the 

 leaf prints of the grand old forests which dur- 

 ing that age of semi-tropical climate covered 

 those lake shores. The marine rocks form 

 the outer rim or shore-line of what was in 

 those early times a lake of irregular outline, 

 extending from Kern Creek hill on the west 

 to Canyon City on the east, and from the hills 

 north of the John Day river to the Crooked 

 River valley on the south. Within this lake 

 depression whose former muddy sediment is 

 now elevated into chalky hills, so despised for 



