DEPARTMENT OF THE INTERIOR
UNITED STATES GEOLOGICAL SURVEY

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Base from U.S. Geological Survey
Gambacorta Peak , 1968, and Schmidt Hills

, 1969

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SCALE 1:250,000

Prepared by the
U.S. GEOLOGICAL SURVEY
under the auspices of the
NATIONAL SCIENCE FOUNDATION

20 Statute Miles

5 Oo) 5 10 is
5 ° 5 10 15 20 25 30 kilometers
a

5 ° 5 10 15 Nautical Miles

60°00"
83°00"

85°00"
60°00"

52°30

84°00"

as*

Polar Stereographic Projection—Standard Parallel 80°14’
CONTOUR INTERVAL 200 METERS—DATUM IS MEAN SEA LEVEL

LOCATION DIAGRAM
30° WEST O° EAST 30°

60°

90°

120°

00"

Compiled from U.S.N.O.0. chart 1706 S, 1965

ISOGONIC LINE DIAGRAM

DOn

DOe

VE DT AN

MEDIAN

SMOW FIELD
cin
PLUTON

(Inferred
at depth).

Geology mapped in 1963-64 by
D. L. Schmidt, P.L. Williams,

W. H. Nelson, and J.R. Ege, and
in 1965-66 by D.L. Schmidt
and W.H. Nelson

75°00"
182"00"———

|
gu 16-20/11|

aae| —

WEST OF GREENWICH

THOMAS GAMBaCORTA
HILLS PEAK

S| CoRoiNeR”
16-20/13| PEAKE’
Su aists9

SCHMIOT
su HILLS:

Sheet numbering system based on International

Map of the World

INDEX TO ADJOINING SHEETS

Zz cars
Mount on 2\z ale
A Coulter count ¥ e Webb Nunataks AR Mount A
000 — ary “ PCS PCE 3000
1000 ~| TANT A TTTT q D RR }- 1000
seatevel Au AHA t WHA HANNE fesstevet
1000 fis}! i Stn Mdla Er a Win WV LL 1000
pe€pu ipEpu p€pu ip€s 4 |€n! DOh: pep
Mi dpe dk 4 {FPP iff oot?
Note: Dikes and sills (units p€b and pCs) in
Precambrian rocks (units pCp and p€pu)
are diagrammatic but are approximately
as depicted in outcrop. 5 5 z é 5 é
<|F 2\5 2|6
a|o alo alo
. ran a
B ne al sat BYP erury ies ° posse 8
METERS. : 1 bof W Caz a €¢ (ent METERS.
2000 A H th Ke Qn 2000
1000 —| eee. / t AW I 1000
SEA LEVEL + ik A TIA TITAN \ (VII [r= SEA LEVEL
NWA We a ACT IN
1000 ~ INURE A NRG ! fii VATE- 1000
‘Ee! pepp! if pepu {| pow’ ] //*Doe | Pep |
5
2\5 2|3
ale °
2\5 2 6
z a|% alo
2 mers
(a Mount Heiser Ridge Z Hawkes Nunatak HIN c
METERS B Nunatak 1 METERS
2000
1000 1000
SEA LEVEL Lp!) Pa es SEA LEVEL
i \\) y
1000 ZA HANN FTN Wil sah cia 1000

pepw” pepw: p€pu

Note: Most folds shown in Precambrian rocks (unit p&p) are diagrammatic.

{|

ATHIANYAN =
Doug iety NEN ea

If {| Doe! DOel

Interior — Geological Survey, Reston, Va.—1978 — G76337

PCg

€gh

ae]

p€pu

CORRELATION OF MAP UNITS

SURFICIAL DEPOSITS

[om |

U.S. ANTARCTIC RESEARCH PROGRAM

SCHMIDT HILLS QUADRANGLE AND PART OF THE
GAMBACORTA PEAK QUADRANGLE

ANTARCTIC GEOLOGIC MAP A-8

Holocene and } QUATERNARY

Pleistocene
SEDIMENTARY AND
VOLCANIC ROCKS INTRUSIVE ROCKS
ANGULAR UNCONFORMITY (WEDDELL OROGENY)
R TRIASSIC(?)
eee PERMIAN (?) AND
oss CARBONIFEROUS (?)
DISCONFORMITY
[ee] + DEVONIAN
DISCONFORMITY(?) | Beacon(?) -
= Supergroup 7
-
Neptine DEVONIAN (’)
Group r TO
ORDOVICIAN (?)
ANGULAR UNCONFORMITY (ROSS OROGENY)
-Upper Cambrian
| CAMBRIAN
+Middle Cambrian
ANGULAR UNCONFORMITY (BEARDMORE OROGENY) 7
Pedy
[ee] + Upper Precambrian | PRECAMBRIAN

DESCRIPTION OF MAP UNITS

SURFICIAL DEPOSITS

MORAINAL DEPOSITS (Holocene and Pleistocene) — Medium- to dark-gray non-
weathered nonsorted debris comprising ablation moraine. Nearly all rock types
in moraine occur in nearby and upslope outcrops; erratics are rare. A thin pebbly
to bouldery pavement several centimeters thick at the surface consists of loose
stones covering permanently frozen drift of fine and coarse debris. Calcium sul-

fate efflorescences form crusts on the-underside of some surface cobbles. Moraines
are associated with an ice level and ice configuration nearly identical to that of the

present day. Scattered erratics of older moraine (not mapped) are found on most
rock slopes and peaks and indicate an older, higher (Tertiary?) level that was more
than 1,000 m above the present-day level

SEDIMENTARY AND VOLCANIC ROCKS

BEACON(?) SUPERGROUP (Triassic? to Ordovician?) — Includes clastic dikes
(unit Re), the Gale Mudstone, Dover Sandstone, and the Neptune Group

GALE MUDSTONE (Permian? and Carboniferous?) — Massive dark-gray diamictite
(tillite) containing abundant dispersed pebbles, cobbles, and boulders of igneous
and sedimentary rocks. A few thin layers of tan silty sandstone and conglomerate
separate thick layers of tillite. The top of the underlying Dover Sandstone is
grooved, and the tops of several boulder pavements within the Gale are well stri-
ated in a consistent southerly direction that suggests ice movement to the south.
Probably several times as thick as a measured 315 m. Top not exposed

DOVER SANDSTONE (Devonian) — White thick even-bedded medium-grained
quartz sandstone containing conspicuous but widely scattered floating quartz
pebbles; weathers tan. Many beds are orthoquartzite; some beds are coarsely
crossbedded. Conglomerate, 0.3-7 m thick, of rounded quartz pebbles at the base
contains sparse to locally abundant black pebbles of sedimentary phosphate. No
fossils found in map area, but in the Patuxent Range 150 km southwest of the
map area, the Dover contains several thin sandy carbonaceous lenses with a
Middle Devonian microflora and a poorly preserved Devonian macroflora of
Haplostigma(?) and “Cyclostigma-type” (Schopf, 1968; Rigby and Schopf, 1969)
About 1,200 m thick

NEPTUNE GROUP (Devonian? to Ordovician?) — Includes the Heiser Sandstone,
Elbow Formation, Elliott Sandstone, Brown Ridge Conglomerate, and Neith
Conglomerate

HEISER SANDSTONE — Well-bedded light-green quartz sandstone that is slightly
more silty than the Dover; weathers brown. In places, rhythmically bedded pairs
of silty sandstone and quartzite beds, 0.3-1 m thick, are common. Formation is
characterized by many beds containing tubular burrows, %4-1 cm in diameter,
oriented vertically to bedding. About 320 m thick

ELBOW FORMATION ~ Interbedded red argillaceous siltstone and light-gray fine-
grained quartz-rich sandstone in well-bedded alternating layered pairs, 0.3-2 m
thick, that reflect cyclical deposition; beds are well laminated, crossbedding com-
mon, and ripple marks sparse. The red beds are commonly mottled light gray.
About 300 m thick

ELLIOTT SANDSTONE ~ Thick-bedded, commonly crossbedded, pink to buff
coarse-grained quartz-rich sandstone that is cemented by calcite in many places,
especially in lower half, Contains some thin interbeds of buff conglomerate, con-
glomeratic sandstone, and red siltstone and shale. A basal conglomerate, locally
as thick as 3 m, contains abundant volcanic pebbles. Volcanic-derived quartz and
volcanic clasts predominate in lower part of formation but decrease in amount
gtadationally upward. Thickness ranges from about 1,400 m near the Gamba-
corta eruptive center near Gambacorta Peak to zero in the northern Neptune
Range

Rhyolite breccia member — Dark-reddish-brown to buff pyroclastic autolithic flow
breccia of porphyritic rhyolite; consists of moderately welded, closely packed,
subangular lithic fragments commonly 2-8 cm across. Occurs about 30 m above
the base of the formation near Wiens Peak where it is about 70 m thick. May be
genetically related to the Gambacorta Formation (€g) and Median Granite (Em).
Rb-Sr whole-rock data from one sample suggest an age similar to that of the
Gambacorta Formation (Eastin, 1970, p. 87-93, 112)

BROWN RIDGE CONGLOMERATE -— Poorly bedded to massive, poorly sorted,
coarse, dark-reddish-brown conglomerate containing a few thin red sandstone
beds and lenses. Locally in the lower part the conglomerate is green. Clasts con-
sist of locally derived older sedimentary and volcanic rocks that are as much as
1 m in diameter; clasts of plutonic igneous rocks are absent. Conspicuous angu-
lar white quartz clasts derived from abundant veinlets in the Patuxent Formation
are characteristic. Near the eruptive center of the Gambacorta Formation in the
southern Neptune Range, the conglomerate consists chiefly of volcanic detritus;
toward the north and west, away from the volcanic center, the volcanic content
gradationally diminishes to nearly zero. Thickness ranges from zero to more than
800 m

NEITH CONGLOMERATE ~— Poorly bedded to massive, poorly sorted, coarse,
reddish-brown conglomerate interbedded with moderately well bedded coarse-
grained reddish-brown sandstone. Clasts are derived chiefly from underlying
sedimentary formations; clasts of plutonic rocks are minor or absent; Gamba-
corta volcanic clasts are absent; angular white quartz clasts from veinlets in the
Patuxent Formation are conspicuous at the base. Basal part locally is dominantly
conglomeratic and in places exceedingly thick; the upper part is dominantly
sandstone. These rocks, which crop out on Neith Nunatak and are equivalent to
the Elliott Sandstone and the Brown Ridge Conglomerate, are here named the
Neith Conglomerate. Exact thickness is not established but locally may be as
much as 1,000 m

WIENS FORMATION (Upper Cambrian) — Interbedded dark-green and dark-
reddish-brown thin-bedded shale, siltstone, and fine-grained sandstone contain-
ing several beds, 3-10 m thick, of light-gray oolitic limestone. Lower part is
interfingered with volcanic sediments of the upper part of the Gambacorta
Formation. Nondiagnostic trace fossils occur sparsely on bedding planes. Thick-
ness is less than 300 m in the southern Neptune Range but considerably more in
the northern Neptune Range

GAMBACORTA FORMATION (Upper Cambrian) — Interbedded dark-brown,
reddish-brown, and light-green rhyolitic to dacitic volcanic rocks that include
ash flows, volcanic breccias, pyroclastic flows, lava flows, and agglomerates.
Light-green ash-fall deposits and sandstones of reworked volcanic debris are
abundant near top and bottom of formation. The Gambacorta Formation con-
stitutes a volcanic complex that erupted from a center in the southern Neptune
Range near Gambacorta Peak, where the formation is probably thicker than
1,500 m; the formation thins away from this center; it is about 160 m thick
40 km to the north. The Gambacorta Formation is divided into six members, of
which only the Hawkes Rhyodacite Member can be shown at the map scale.
Rb-Sr whole-rock data from 10 samples of the Gambacorta Formation, includ-
ing the Hawkes Rhyodacite Member, suggest an isochron age of 510£35 m.y.
(Eastin, 1970, p. 87-93, 112)

Hawkes Rhyodacite Member — Dark-green porphyritic rhyodacitic welded tuff
containing 30 percent coarse broken quartz, potassium feldspar, and plagioclase
phenocrysts, as well as abundant inclusions of compacted pumice. Fine-grained
groundmass is recrystallized but commonly shows a relic eutaxitic shard structure.
Rock is locally oxidized to reddish-brown color. The member, as an intracaldera
phase more than 1,000 m thick, is exposed at Mount Hawkes and Hill Nunatak
and probably fills the Iroquois caldera beneath the Beacon strata in the inter-
vening area, The caldera, here named for the Lroquois Plateau, is defined by a
10-milligal gravity low (Behrendt and others, 1974, pl. 1) and by a set of con-
centric border faults exposed near Mount Hawkes. A thin outflow phase of the
Hawkes Rhyodacite Member, an ash-flow tuff, occurrs outside the caldera area.

NELSON LIMESTONE (Middle Cambrian) — Dark-gray thick-bedded massive lime-
stone, commonly bleached light gray, constitutes the principal middle part of
the formation. Above and below are thin-bedded light-gray algal(?) limestone and
argillaceous limestone as well as thin irregular beds of yellow limy siltstone; some
limestone is oolitic, pisolitic, or nodular. A basal dark-reddish-brown conglomer-
ate, several centimeters to 30 m thick, is locally overlain by red-brown sandstone
as much as 20 m thick; the clasts are derived from the Patuxent Formation and
characteristically contain conspicuous pebbles of white vein quartz. Thickness
is 200-300 m. A Middle Cambrian age is indicated by trilobites found about 4 km
south of Nelson Peak (Palmer and Gatehouse, 1972)

PATUXENT FORMATION (upper Precambrian) — Well-bedded, generally rhythmi-
cally interbedded, medium- to dark-grayish-green medium-grained argillaceous

metasandstone (metasubgraywacke) and slate; a few gritstone and intraformational

sand-pebble and shale-pebble conglomerates form discontinuous beds and lenses.
Channel fillings, graded bedding, crossbedding, laminated bedding, and sole mark-
ings are locally well preserved. This entirely clastic section of Patuxent Formation.
is mapped in the Neptune Range east of the fault of Roderick Valley. To the west
in the Schmidt and Williams Hills three volcanic members, the Gorecki, Williams,
and Pillow Knob Members, are intercalated with clastic rocks similar to those of
the Patuxent Formation east of the fault of Roderick Valley. The stratigraphic
positions of the three members within the Patuxent Formation are not under-
stood because of intensive folding and faulting prior to extensive erosion beneath
the Cambrian angular unconformity and because the base of the Patuxent Forma-
tion has not been observed. The age of the formation is probably late Pre-
cambrian based on an isotopic date of the Gorecki Felsite Member in the Schmidt
and Williams Hills (Eastin, 1970, p. 100-103). The entire formation is regionally
metamorphosed to the greenschist facies and is moderately well to well cleaved.
Deformation and absence of distinctive marker beds of regional extent within the
formation preclude accurate determination of thickness, but a minimum exposed
structural relief of about 1,000 m in the Patuxent Range and widespread distribu-
tion throughout the Pensacola Mountains suggest a thickness of more than
10,000 m

Gorecki Felsite Member — Light- to medium-gray porphyritic felsic tuffs and flow
breccias, 2-100 m thick, are sparsely intercalated with sandstone and slate in the
Schmidt and Williams Hills. Some tuffs exhibit well-developed eutaxitic shard
structure suggesting an ash-flow origin. Chemical composition of the rocks ranges
from dacite to rhyolite. The Gorecki Felsite Member is here named for Mount
Gorecki, where its type section is located. Rb-Sr whole-rock data from four
samples suggest an isochron age of 1,210476 m.y., but four other samples give a
reset date of 48846 m.y. (Eastin, 1970, p. 101-103). The aggregate thickness of
exposed felsite is probably less than several hundred meters. Flows are shown
schematically on map

Williams Basalt Member — Dark-gray to dark-green basalt flows intercalated with
sandstone and slate in the Williams Hills. Flows are 2-30 m thick and constitute
about 15 percent of the exposed rock in the Williams Hills; aggregate thickness
of basalt may be 1,000 m. In places flows may be erroneously mapped as diabase
of Schmidt Hills (p€s). Most flows are shown schematically on the map. The
Williams Basalt Member is here named for the Williams Hills, where its type sec-
tion is located

Pillow Knob Basalt Member — Dark-gray to dark-green massive pillow basalt in the
Schmidt and Williams Hills. Pillows range from 5 cm to 1 m across and are set in
an argillaceous or locally calcareous matrix. Layering is poorly defined. The total
thickness may be several hundred meters. The Pillow Knob Basalt Member is here
named for Pillow Knob, where its type section is located

Patuxent Formation and diabase of Schmidt Hills, undivided (upper Precambrian) —

Unit is mapped in Schmidt and Williams Hills where outcrop was not field checked

and in areas concealed by snow

INTRUSIVE ROCKS

Rey

CLASTIC DIKES (Triassic?) — Light-buff to dark-gray, mostly medium-grained,

quartz-rich sandstone dikes cutting rocks as young as the Dover Sandstone
(Dd); some dikes may be older because some dike rock is well cleaved and
cuts rocks as old as the Patuxent Formation(p€p). Dikes range in width from
0.1 to 5 m. The direction of intrusion, where determined, is downward; on
Mount Feldkotter, dike rock derived from tillite of the Gale Mudstone cuts the
Dover and Heiser Sandstones at least 1,300 m stratigraphically below the Gale.
The younger dikes were probably emplaced during the early Mesozoic orogeny

€m

MEDIAN GRANITE (Upper Cambrian) — Light-gray and light-red coarse-grained

biotite granite that is not exposed but is derived from the inferred Median pluton,
which is estimated to underlie a large area beneath the Median Snowfield west of
Serpan Peak. The Serpan Gneiss (€s) is the exposed border phase of the pluton.
The location and size of the pluton can be estimated from a negative gravity
anomaly of at least 30 mgal (Behrendt and others, 1974, p. 11) and by the distri-
bution of granitic erratics in moraines down-glacier from the inferred pluton.
Rb-Sr whole-rock data from three samples suggest an isochron age of 530434 m.y.
(Late Cambrian) (Eastin, 1970, p. 97; Schmidt and Ford, 1969)

SERPAN GNEISS (Upper Cambrian) — Dark- to light-gray banded gneiss of sphene-
bearing hornblende-biotite granodioritic and biotite granitic composition. Rb-St
whole-rock data from eight samples suggest an isochron age of $25+15 m.y.
(Eastin, 1970, p. 97). The Serpan Gneiss is here named for Serpan Peak, which
is its only known outcrop and where it is more than 700 m wide; it is believed
to be a border phase of the Median Granite (Em)

DIKES, SILLS, AND PLUGS (Upper Cambrian) ~ Buff to drab-green porphyritic
felsic intrusive rock; commonly with aphanitic groundmass and chilled margins.
Dikes and sills commonly 1-5 m wide; plugs 5-40 m across. Most rocks are
probably related to the Gambacorta Formation and Median Granite. A Rb-Sr
whole-rock date of the plug on Baker Ridge indicates Cambrian age (Eastin,
1970, p. 92)

Aplite dike (Upper Cambrian) — Light gray; 0.3 m wide; cuts Serpan Gneiss at
Serpan Peak. Rock is probably related to the Median Granite

Breccia dike (Upper Cambrian?) ~ Dark-reddish-brown to light-reddish-brown and
dark-green, aphanitic to finely crystalline mafic intrusive breccia, highly contam-
inated by carbonate; intrudes Nelson Limestone. Age is uncertain

BASALTIC DIKES AND SILLS (upper Precambrian) — Dark-gray to dark-green basalt-.

ic rock in bodies 1-2 m wide; mapped in the western Neptune Range; has well-
developed regional axial-plane cleavage and is intrusive into the Patuxent Forma-
tion. Age uncertain but probably Precambrian

(ee) DIABASE OF SCHMIDT HILLS (upper Precambrian) — Dark-gray olivine-bearing

10-20 80-90 5-10
90

augite-labradorite alkali basalt, well differentiated in thick sills intrusive into
Patuxent Formation in the western Neptune Range. Sills are 2-150 m thick and
constitute about 30 percent of the exposed rock in the Schmidt Hills. Alteration
to chlorite and more sodic plagioclase is extensive, and rock is commonly in-
tensely folded and sheared with the rocks of the Patuxent Formation. Age is
probably slightly younger than that of the Patuxent Formation; Rb-Sr whole-
rock data on six samples suggest an estimated isochron age of 77859 m.y.
however, a 2-point isochron suggests a possible maximum age of 1,267 my.
(Eastin, 1970, p. 107). In places may be erroneously mapped as Williams Basalt
Member of Patuxent Formation. Most of the sills are shown schematically on
the map

Contact — Mostly exposed in areas of bedrock outcrop; inferred where covered by
ice, snow, and moraine

Contact of Median Granite — Concealed; inferred location based on negative gravity
anomaly (Behrendt and others, 1974, p. 11)

High-angle fault — Showing dip. Inferred where covered by ice, snow, and moraine.
U, upthrown side; D, downthrown side. Half arrows indicate probably direction
of horizontal movement

Bedding-plane fault — Sawteeth on upper plate. Shear on bedding planes is common,
especially at Cambrian-Precambrian unconformity. Fault shown only where move-
ment is inferred to be significant

Main ring-fracture of the Iroquois caldera — Inferred position based in part ona
10-mgal gravity low (Behrendt and others, 1974, pl. 1)

Major folds in Phanerozoic rocks — Showing crestline or troughline and plunge.
Inferred where covered by ice and snow and in Precambrian rocks. Plunges veri-
fied from stereographic plots

Anticline — Showing plunge

Syncline — Showing plunge
Asymmetric anticline — Showing dip of limbs; short arrow indicates steeper limb
Overturned syncline — Showing direction of dip of limbs

Minor folds — Showing plunge
Anticline — Showing crestline

Syncline — Showing troughline
Multiple folds — Showing axial trend

Antiform — Inferred anticlinorial fold. Involves refolded, previously isoclinally folded
Patuxent Formation in Schmidt Hills

Strike and dip of beds
Horizontal

Inclined
Vertical
Overturned

Flow foliation — Showing strike and dip in volcanic rocks
Strike and dip of principal cleavage
Inclined

Vertical

Strike and dip of secondary cleavage
Inclined

Vertical
Strike of vertical joint

Stereogram summation of fold and cleavage — Showing average axial trend and com-
mon range of plunge of abundant isoclinal folds and average strike and common
range of dip of cleavage in Patuxent Formation in Schmidt and Williams Hills

Bedrock outcrop

SELECTED REFERENCES

Barrett, P.J., 1970, Stratigraphy and paleontology of the Beacon Supergroup in the Transantarctic
Mountains, Antarctica, in Haughton, S.H., ed., Second Gondwana Symposium, I.U.G.:
Johannesburg, 1970: South Africa Geol. Soc., Proceedings and Papers Pretoria, p. 249-256.

Beck, M.E., Jr. and Schmidt, D.L., 1971, Reset direction of remanent magnetization for Upper
Cambrian rhyodacite welded tuff, Pensacola Mountains, Antarctica, in Geological Survey
research, 1970: U.S. Geol. Survey Prof. Paper 700—C, p. C174—178.

Behrendt, J.C., Henderson, J.R., Meister, Laurent, and Rambo, W.L., 1974, Geophysical in-
vestigations of the Pensacola Mountains and adjacent glacierized areas of Antarctica: U.S.
Geol. Survey Prof Paper 844, 28p.

Behrendt, J.C., Rambo, W.L., Henderson, J.R., and Meister, Laurent, 1973, Simple Bouguer
gravity and generalized geologic map and aeromagnetic profiles of the Schmidt Hills quad-
rangle and part of the Gambacorta Peak quadrangle, Antarctica: U.S. Geol. Survey Geophys.
Inv. Map GP—889, scale 1:250,000.

Eastin, Rene, 1970, Geochronology of the basement rocks of the central Transantarctic Moun-
tains, Antarctica; Pensacola Mountains, in Faure, Gunter, Eastin, Rene, Gunner, J.D., Hill,
R.L., Jones, L.M., and Elliot, D.H., Studies in the geochronology and geochemistry of the
Transantarctic Mountains: Ohio State Univ., Columbus, Research Foundation Report no.
RF 2411, p. 67-114.

Ford, A.B., 1972, The Weddell orogeny — latest Permian to early Mesozoic deformation at the
Weddell Sea margin of the Transantarctic Mountains, in Adie, R.J., ed., Antarctic geology
and geophysics: Oslo, Universititetsforlaget, p. 419-425.

Frakes, A.L., Matthews, J.L., and Crowell, J.C., 1971, Late Paleozoic glaciation: Part III,
Antarctica: Geol. Soc. America Bull., v. 82, no. 6, p. 1581-1604.

Huffman, J.W., and Schmidt, D.L., 1966, Pensacola Mountains project: Antarctic Journ.

US., v. 1, no. 4, p. 123-124.

Palmer, A.R., and Gatehouse, C.G., 1972, Early and Middle Cambrian trilobites from Antare-
tica: U.S. Geol. Survey Prof. Paper, 456—D, 37p.

Rigby, J.F., and Schopf, J.M., 1969, Stratigraphicimplications of Antarctic paleobotanical
studies, in Amos, A.J., ed., Gondwana stratigraphy, I.U.G.S. symposium, Buenos Aires,
October 1967: UNESCO Earth Sci. Ser. v.2, Paris, p. 91-106.

Schmidt, D.L., 1964, Geology of the Pensacola Mountains: U.S. Antarctic Projects Office
Bull. v. 5, no. 10, p. 98-101.

1969, Precambrian and lower Paleozoic igneous rocks, Pensacola Mountains, Ant-
arctica: Antarctic Jour. U.S., v. 4, no. 5, p. 203-204.

Schmidt, D.L., and Ford, A.B., 1969, Geology of the Pensacola and Thiel Mountains, in Bush-
nell, V.C., and Craddock,Campbell, eds., Geologic maps of Antarctica, Antarctic Map Folio
Ser., Folio 12, Sheet 5: American Geog. Soc., New York.

Schmidt, D.L., and Williams, P.L., 1969, Continental glaciation of late Paleozoic age, Pen-
sacola Mountains, Antarctica, in Amos, A.J., ed., Gondwana stratigraphy, I.U.G.S. Sym-
posium, Buenos Aires, October 1967: UNESCO Earth Sci. Ser., v.2, Paris, p. 617-649.

Schmidt, D.L., Williams, P.L., Nelson, W.H., and Ege, J.R., 1965, Upper Precambrian and
Paleozoic stratigraphy and structure of the Neptune Range, Antarctica, in Geological Survey
research 1965: U.S. Geol. Survey Prof. Paper 525—D, p. D112—D119.

Schopf, J.M., 1968, Studies in Antarctic paleobotany: Antarctic Jour. U.S., v. 3, no. 5, p. 176-177.

Williams, P.L., 1969, Petrology of upper Precambrian and Paleozoic sandstones in the Pensacola
Mountains, Antarctica: Jour. Sed. Pet., v. 39, no. 4, p. 1455-1465.

GEOLOGIC MAP OF THE SCHMIDT HILLS QUADRANGLE AND PART OF THE GAMBACORTA PEAK QUADRANGLE,
PENSACOLA MOUNTAINS, ANTARCTICA

By

Dwight L. Schmidt, Paul L. Williams, and Willis H. Nelson

1978

For sale by Branch of Distribution,

U.S. Geological Survey, 1200 South Eads Street,
Arlington, VA 22202 and Branch of Distribution,
U.S. Geological Survey, Box 25286, Federal Center,
Denver, CO 80225