anes

ef

“fronte The time was laramide, that is late Cretaceous and early

Tertiary. Lower Caste tekes Teles eh were ee Oly folded,

" poste Koneinicecdel uplift is beecoccdea in minor’ folds in Upper

_ Cretaceous formations of the Foothills and in uplifted and tilted
|, plateaus underlain by Upper Cretaceous beds. This uplift was followed

by the devel opment of a peneplain that matches similer plains farther

. South, By analogy, the uplift may be assigned to Eocene time ond the
peneplana tion. to Miocene time,

Another uplift followed, SS ee early in Pliocene time, and
broad lowlands and flering valleys were developed 400 to 500 feet below
the peneplained surface. Late Pliocene uplift initiated the deep |

. dissection of plains and mountains, which increased in tempo until the

“ “dee cover grew to glacial a aaa and the Ice Age had begun.

DESCRIPTIONS a FORMA TIONS

Bible: of: formations:

Li . fs 4 a api .

Ape.) shied: ct Character: #5) 00 41> _ } Thickness
Ki Si : are Efe hy HEN: * + Feet
Recent | Sands, gravels: LOG: &
Pleistocene = ~~ {"  MaIt, “gravel, Sais geet ca “4 “up to 500
Tertiary — - i Clay, lignite ae Harsclelas
Upper Cretaceous Conglomerate and sandstone 600 +
‘Shale and sandstone i 1,500.+
. Lower Cretaceous | isi teeenes sandstone, and if
| - lignitic shale POO St
. Rone Dae ds
Triassic {> Black argillaceous liméstones |...
wh Hed ‘and sandstones’ Ut er OOUrt:
ye sed f Age Laie H
Te Rue ete a Bay SRST RS RT ee Pea OS a
Pennsylvanian or | ; Black chert . Pi neOO +:
Permian -; a : ;
oun ees aren rae ;
Ti a TOOA AR PEE EIT
Mississippian and | Limestone and calcaredus © , 400+
(?) Later i sandstone

| Black argillaceous limestones, |
Mississippian dark shales and sandstones | 2,500 +
I

Devonian and

Silurian and { Limestone and interbedded i
Devonian : sandstone as 000i a

H }

i :