772 THE AMERICAN NATURALIST. [VoL. XXXIII. 
OCK 
FORMATION. 
Rock 
DEFORMATION. 
4 
{ 
ACTION 
OF AIR. 
ACTION 
OF WATER. 
ACTION 
OF LIFE. 
ACTION OF THE 
| EarTH’s INTERIOR. 
f Surfaces polished by wind- 
h own Seras coloring and split- 
|a oduced by sun’s heat, 
Los Sigii: etc. 
( CHEMICAL EROSION. 
Pittings on limestone, gypsum, 
etc 
CHEMICAL ALTERATION. 
Kaolin, clay, limonite, serpen- 
tine, etc. 
CHEMICAL DEPOSITION. 
a. aoe amygdules, ge- 
odes, et 
b. Ís. ‘springs. Travertine, si- 
liceous sinter. : 
lakes. Clay-iron-stone, 
J oölitic limestone. 
d. In seas. Gypsum, anhy- 
MECHANICAL DEPOSITION. 
River gravels, sand and silt; 
beach gravels, sand and silt; con- 
glomerates, sandstones, etc. 
STRATA PHENOMENA. 
Mud cracks, ripple marks, rain- 
prints, etc. 
GLACIAL PHENOMENA. 
Glaciated pebbles, moraine 
sab di scored and polished 
| sur 
f EROSION AND DEPOSITION BY 
PLANT LIFE. 
Rocks pitted by humus acids. 
Coal, peat, lignite, diatomaceous 
earth, petrified wood, etc 
| EROSION AND DEPOSITION BY 
ANIMAL LIFE. 
Rocks bored by mollusks. Ani- 
mal r remains, limestones, chalks, 
etc 
T Volcanic products, ashes, lavas, 
tuffs, etc. 
Folded and crumpled rocks, 
stylolites, slickensides, etc. 
