493909 © - 59 (In pocket)

UNITED STATES DEPARTMENT OF THE INTERIOR
GEOLOGICAL SURVEY

Generalized composite stratigraphic section
in the Katmai area, Alaska

Scale lin =500 ft

AND QUATERNARY

TERTIARY

Eocene

cene

Paleo- |

£
g
z
5
2
3
oO

6000 + ft

hex XX XXX
Kx X XX XX

CRETACEOUS

Cretaceous

Upper

formation

Kaguyak

Upper member

1700+ ft

Middle member

1090 ft

Lower member

2000+ ft

JURASSIC

Jurassic

Upper
Naknek

formation

6000-9000 ft

Chisik
congl. member

Extrusive rocks; chiefly andesite, basalt, and tuff

Continental unit that interfingers with voleanic rocks.
Includes massive conglomerate with pebbles, cobbles,
and boulders of silicic and mafic igneous rock,
chert, silicified tuff, and silicified wood; fine- to
coarse-grained light-gray quartzose sandstone, silt
stone, and plant-bearing mudstone; stringers of
lignite and carbonaceous material; agglomerate
locally near base; rocks contain’ Metasequoia
occidentalis (Newberry) Chaney, Alnus alaskana
Newberry, Magnolia ? 8p. Glyptostrobus dakotensis
(Brown), Betula sp., Corylus sp. and Gereidiphyllum
ellipticum (Newberry) Brown. Probable equivalent
to Kenai formation

‘

Interbedded very fine-to fine-grained noncaleareous
argillaceous ferruginous sandstone, siltstone, and
silty shale; ironstone rare; carbonaceous material

Rhythmically bedded sandstone, siltstone, and silty shale;
fine- to medium-grained moderately argillaceous
sandstone; large spheroidal noncalcareous. silt
stone coneretions locally alined on bedding planes;
dark-gray platy to hackly fracturing silty shale;
dense dark-gray siltstone; sandstone locally exhibits
a ropy type of flow structure; sandstone in units up
to 10 feet thick with siltstone and silty shale units
up to 8 feet thick.

Interbedded light-reddish-weathering fine-grained
dirty sandstone, medium-gray platy silty shale,
and dense siltstone; sandstone contains shale galls

Massively bedded medium-gray very dense siliceous,
noncalcareous siltstone locally breaking down to
hackly fracturing silty shale containing calcite
veining and large spheroidal limy dark-gray
locally pyritized siltstone concretions alined on
bedding planes; concretions carry abundant
Inoceramus ef. I, kusiroensis Nagao and Matumoto,
Inoceramus ‘cf. I. shikotanensis Nagao and
Matumoto, Lytoceras (Gaudryceras) sp.,Pachydiscus
(Neodesmoceras) sp. Nemodon sp. Anomia ef. A.
vancouverensis Gabb and Pleuromya sp.

Interbedded massive gray-green well-indurated silt-
stone and sandstone; Aucella sp. common through-
out sequence; rock locally coquinoid

Interbedded green-gray fine-grained generally
impervious sandstone, siltstone, and sandy shale;
siltstone in 4- to 2-inch beds; sandstone blocky
to slabby; Aucella sp. common throughout sequence

Coarse-grained noncaleareous green-gray arkosic
sandstone; estimated moderate porosity but low
ermeability; detritus consists of well-rounded
Pairly well sorted green and gray chert, white
quartz, and feldspar. _Interbedded massive gray
siltstone and lenses of conglomeratic sandstone;
section contains abundant Aucella rugosa (Fischer),
Aucella mosquensis (von Buch), and less commonly
Pleuromya sp. and Meleagrinella sp.

Marine conglomerate consisting of large well-rounded
to angular granite, chert, and mafie igneous cobbles
in a green fossiliferous sandstone matrix; boulders
up to 2 feet in diameter; Aucella sp. common in
the green sandstone matrix and in the intercalated
coarse-grained sandstone beds

Grosvenor Lake
Stratigraphic section 1
Scale lin =200ft

Unit
no.

Upper Jurassic

Naknek formation

Partly covered interval

Partly, covered interval

10

Partly covered
interval

Specimen
no.

25277

25278

Aucella. sp.

Auucella sp.

Aucella sp.

Aucella sp.

Aucella sp.

Aucella rugosa (Fischer)
Aucella mosquensis (von Buch)
Pleuromya sp.

Aucella rugosa (Fischer)
Aucella mosquensis (von Buch)
Meleagrinella sp.

Aucella mosquensis (von Buch)
Aucella rugosa (Fischer)
Pleuromya sp.

Aucella sp.

Kaguyak Bay
Stratigraphic section 2
Scale 1 in=200ft

Unit
no.

Upper Cretaceous

Kaguyak formation

Upper member

Partly covered interval

s
s
=
3
2
5
g
3
8

Middle member

Partly covered interval 34 ]9

Lower member

NON RR
RA aS)

12

Covered interval

Covered interval

Partly covered interval

Covered interval

Naknek formation

Specimen
no.

54 AKe 45

25283

25282

25281

25280

Inoceramus ef. 1, kusiroensis
Nagao and Matumoto

Inoceramus cf. I. shikotanensis
‘Nagao and Matumoto

Lytoceras (Gaudryceras) sp.

Pachydiscus (Neodesmoceras) sp.

Inoceramus ef. I, kysiroensis
‘Nagao and Matumoto

Nemodon sp.

Anomia cf. A. vancouverensis
Gabb

Inoceramus sp.

Pleuromya? sp.

Cape Nukshak
Stratigraphic section 3
Scale 1 in=100 ft

Unit Speci
nit specimen
54 AKe 36 © Metasequoia occidentalis
(Newberry) Chaney
Alnus alaskana Newberry
4&
>
Z|. E 54 AKe 35 — Metasequota occidentalis
<)ele (Newberry) Chaney
|g) Alms alasiena Newberry
ui i
F| |¢
g
8

EXPLANATION

Conglomerate

Sandstone

Shaly sandstone

Silty shale

Shale or claystone

Clay shale or mudstone

Coal

Carbonaceous material

Coal lenses

@Q
fon

Concretions

RXR RK
XXX XXX
x XXX XX

Voleanic rock

Igneous sill

STRATIGRAPHIC SECTIONS IN THE MOUNT KATMAI AREA, ALASKA

BULLETIN 1058 PLATE 32

Geographic Harbor
Stratigraphic section 4

Scale Lin =20 ft

TERTIARY

Eocene

Unit Specimen
To n0.
54 AKe 17Li
54 AKe 16F = Magnolia? sp.
54 AKe 15Li
54 AKe 14Li
4 =
z :
wo 2
Elis 5
=
FI 2
2 H
3 g
oO
54 AKe 13F — Glyptostrobus dakotensis Brown
Dicotyledonous leaves resembling
lnus
Betula sp.
Corylus sp.