Surface Geology - North Dakota · slo p ew ah dim ntc y r. R v (gravel), and cobble and boulder lag...
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( 20 ! ( 20 ! ( 20 24K: Jmtn - sg Cartographic Compilation: Elroy L. Kadrmas 98 o 45 ' 00 " 47 o 00 ' 00 " 98 o 37 ' 30 " 98 o 37 ' 30 " 98 o 45 ' 00 " 46 o 52 ' 30 " 46 o 52 ' 30 " 47 o 00 ' 00 " Surface Geology Jamestown Quadrangle, North Dakota North Dakota Geological Survey John P. Bluemle, State Geologist Robert F. Biek 1994 (FRIED ) (SPIRITWOOD LAKE) (BUCH A NA N) (ELDRIDGE SE) (YPSILANTI) (ELDRIDGE) (HO MER) (BLOO M) MN 9 o 1975 Magnetic North Declination at Center of Sheet Jamestown Quadrangle, North Dakota UNIT DESCRIPTIONS QUATERNARY SYSTEM RECENT OAHE FORMATION Sand, silt, clay, and gravel; poorly sorted; shaly. Strongly resembles till from which it is derived, though is less well compacted and contains scattered organic debris. Deposited on steeply sloping valley walls. Generally less than 6 feet thick. (Mapped only where it obscures Pierre Formation; elsewhere incorporated with river-eroded glacial sediment. Below high-water level of reservoirs, it has been reworked and sorted by lacustrine processes.) Silt, clay, sand, and disseminated organic debris; dark colored; typically very silty and obsurely bedded, locally planar to cross- bedded. Near valley walls commonly overlain by apron of colluvial and slopewash sediment. Deposited in modern river channels and floodplains. Generally less than 12 feet thick. Modern River Channel and Overbank Sediment Qa1 Slopewash (Fan Morphology) Qa Sand, silt, clay, and gravel derived from river-eroded till; poorly sorted. Forms gently sloping apron that grades into overbank sediments of valley floor. Deposited by alluvial and slopewash processes at base of valley walls. Generally less than 10 feet thick. Colluvium Qc Silt, clay, and organic debris; planar to obscurely bedded; dark brownish black; typically greenish gray and sandy at base. Deposited in modern ponds and sloughs. Generally less than 6 feet thick. Pond and Slough Sediment Ql Landslide formed in glacial sediment (till). Characteristic hummocky topography slightly subdued by erosion. Mapped along Pipestem Creek (Section 23, T140N R64W). Smaller, recent landslides shown with a symbol. Landslide Deposits Ql s Pebbly sand, silt, and clay. Fill used to build dams, road bases, and other man-made structures. Fill Qf Pebbly sand, silt, and clay with abundant cobbles and boulders; unsorted; unbedded; shaly. Near the James and Pipestem River valleys, commonly contains a discontinuous veneer of sand. Surface is gently undulating to hummocky. Deposited by glacial ice; multiple-event deposits as much as 200 feet thick. Qt Undisturbed Glacial Sediment (Till) PLEISTOCENE COLEHARBOR GROUP Glacial sediment eroded by meltwater rivers. Veneer of river and slopewash sediment commonly present. River sediments (sand and gravel), and cobble and boulder lag deposits, often exposed on promontories. Forms steep valley walls. River-Eroded Glacial Sediment (Till) Qtr Sand and gravel; moderately to very poorly sorted, locally with inclusions of till; shaly. Deposited by meltwater streams flowing within, on, or under the glacier (eskers) or at or near the ice margin (kames). Up to 30 feet thick. Ice-Contact Stream-Channel Sediment Qe Sand and gravel; moderately to poorly sorted; crossbedded to planar bedded; surfaces are flat to moderately sloping. Deposited by meltwater rivers. Generally less than 10 feet thick. River Channel Sediment Qa3 Qk River channel sediment as above. Forms level to gently sloping terraces, typically on inside bends of meanders. Deposited by meltwater rivers. As much as 45 feet thick above modern channels. River Channel Sediment Qa2 CRETACEOUS SYSTEM Shale, medium gray to light olive gray, fissile, flaky to blocky, generally non-calcareous. Contains several thin (to 5 centimeters (2 inches)) grayish yellow bentonite beds. Concretions - light olive gray micrite (fine grained, dirty limestone) that weathers to a moderate yellow brown to brownish black, and brownish black to moderate yellowish brown iron-manganese or limonitic concretions - are common along certain horizons. Highly jointed with iron-manganese stains on joint surfaces; joints locally calcite cemented; horizontal bedding locally deformed by glacial ice. Probably about 350 feet thick. (DeGrey Member(?).) Marine Offshore Sediment (Bedrock) Kp PIERRE FORMATION Geologic Symbols Known contact between two geologic units Approximate contact between two geologic units !!!!!!!!!!! !!!!!! Subcrop of Pierre Formation Transverse Marginal Ridge (Washboard Moraine) Small Landslide 6 R. 63 W. R. 64 W. T. 1 41 N . T. 1 40 N . T. 1 40 N . T. 1 39 N . R. 63 W. R. 64 W. Stand ard Parallels 46 o 52 ' 30 " and 47 o 00 ' 00 " Lambert Conformal Conic Projection 1927 North American Datum 0 0.5 1 Miles 1:24,000 Scale ! ( Other Features Water U. S. Highway £ ¤ 52 § ¨ ¦ Interstate Highway 94 State Highway 20 Paved Road Unpaved Road All maps areas not coded are (Ql) pond and slough sediment.
Transcript of Surface Geology - North Dakota · slo p ew ah dim ntc y r. R v (gravel), and cobble and boulder lag...
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24K: Jmtn - sg
Ca rtographic Compila tion: Elroy L. Ka drma s
98o 45' 00"
47o 00' 00"
98o 37' 30"
98o 37' 30"98o 45' 00"46o 52' 30" 46o 52' 30"
47o 00' 00"
Surface Geology
Jamestown Quadrangle, North Dakota
North Dakota Geological SurveyJohn P. Bluemle, State Geologist
Robert F. Biek1994
(FRIED) (SPIRITWOOD LAKE)
(BUCHANAN)
(ELDRIDGE SE) (YPSILANTI)
(ELDR
IDGE
)
(HOMER)
(BLO
OM)
MN9o
1975 Magnetic North Declinat ion at C enter of Sheet
Jamestown Quadrangle, North Dakota
UNIT DESCRIPTIONSQUATERNARY SYSTEM
RECENTOAHE FORMATION
Sand, silt, clay, and gravel; poorly sorted; shaly. Strongly resemblestill from which it is derived, though is less well compacted andcontains scattered organic debris. Deposited on steeply slopingvalley walls. Generally less than 6 feet thick. (Mapped only where itobscures Pierre Formation; elsewhere incorporated with river-erodedglacial sediment. Below high-water level of reservoirs, it has beenreworked and sorted by lacustrine processes.)
Silt, clay, sand, and disseminated organic debris; dark colored;typically very silty and obsurely bedded, locally planar to cross-bedded. Near valley walls commonly overla in by apron of colluvialand slopewash sediment. Deposited in modern river channelsand floodplains. Generally less than 12 feet thick.
Modern River Channel and Overbank SedimentQa1
Slopewash (Fan Morphology)QaSand, silt, clay, and gravel derived from river-eroded till; poorlysorted. Forms gently sloping apron that grades into overbanksediments of valley floor. Deposited by alluvial and slopewashprocesses at base of valley walls. Generally less than 10 feetthick.
ColluviumQc
Silt, clay, and organic debris; planar to obscurely bedded; darkbrownish black; typically greenish gray and sandy at base. Depositedin modern ponds and sloughs. Generally less than 6 feet thick.
Pond and Slough SedimentQl
Landslide formed in glacial sediment (ti ll). Characteristic hummockytopography slightly subdued by erosion. Mapped along PipestemCreek (Section 23, T140N R64W). Smaller, recent landslides shownwith a symbol.
Landslide DepositsQls
Pebbly sand, silt, and clay. Fill used to build dams, road bases, andother man-made structures.
FillQf
Pebbly sand, silt, and clay with abundant cobbles and boulders;unsorted; unbedded; shaly. Near the James and Pipestem Rivervalleys, commonly contains a discontinuous veneer of sand.Surface is gently undulating to hummocky. Deposited by glacialice; multiple-event deposits as much as 200 feet thick.
Qt Undisturbed Glacial Sediment (Till)
PLEISTOCENECOLEHARBOR GROUP
Glacial sediment eroded by meltwater rivers. Veneer of river andslopewash sediment commonly present. River sediments (sand andgravel), and cobble and boulder lag deposits, often exposed onpromontories. Forms steep valley walls.
River-Eroded Glacial Sediment (Till)Qtr
Sand and gravel; moderately to very poorly sorted, locally withinclusions of ti ll; shaly. Deposited by meltwater streams flowingwithin, on, or under the glacier (eskers) or at or near the ice margin(kames). Up to 30 feet thick.
Ice-Contact Stream-Channel SedimentQe
Sand and gravel; moderately to poorly sorted; crossbedded to planarbedded; surfaces are flat to moderately sloping. Deposited bymeltwater rivers. Generally less than 10 feet thick.
River Channel SedimentQa3
Qk
River channel sediment as above. Forms level to gently slopingterraces, typically on inside bends of meanders. Deposited bymeltwater rivers. As much as 45 feet thick above modern channels.
River Channel SedimentQa2
CRETACEOUS SYSTEM
Shale, medium gray to light olive gray, fissile, flaky to blocky,generally non-calcareous. Contains several thin (to 5 centimeters (2inches)) grayish yellow bentonite beds. Concretions - light olive graymicrite (fine grained, dirty limestone) that weathers to a moderateyellow brown to brownish black, and brownish black to moderateyellowish brown iron-manganese or limonitic concretions - arecommon along certain horizons. Highly jointed with iron-manganesestains on joint surfaces; joints locally calcite cemented; horizontalbedding locally deformed by glacial ice. Probably about 350 feetthick. (DeGrey Member(?).)
Marine Offshore Sediment (Bedrock)Kp
PIERRE FORMATION
Geologic SymbolsKnown contact between two geologic units
Approximate contact between two geologic units
! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! Subcrop of Pierre Formation
Transverse Marginal Ridge (Washboard Moraine)
Small Landslide6
R. 63 W.R. 64 W.
T. 1 41 N.
T. 1 40 N.
T. 1 40 N.
T. 1 39 N.
R. 63 W.R. 64 W.
Stand ard Parallels 46 o 52' 30" and 47o 00' 00"
Lambert Co nformal Conic Projection1927 No rth American Datum
0 0.5 1Miles
1:24,000Scale
!(
Other FeaturesWater
U. S. Highway£¤52
§̈¦ Interstate Highway94
State Highway20
Paved RoadUnpaved Road
All maps areas not coded are (Ql) pond and slough sediment.
