border: A polygon that encompasses the geographic extent of the data observations ContactsAndFaults: Line features depicting faults and geologic contacts GenericPoints: A point file that provides locations, symbology, and labels for point features other than geochronology, stations, or orientation points. GeochronPoints: Geochronology sample location points MapUnitPolys: Polygons that record the distribution of mapped or interpreted geologic units
Reger, R.D., Stevens, D.S.P., and Koehler, R.D., 2015, Surficial geology of the Tyonek area, south-central Tyonek Quadrangle, Alaska: Report of Investigation RI 2015-7, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.Online Links:
This is a vector data set.
Planar coordinates are encoded using coordinate pair
Abscissae (x-coordinates) are specified to the nearest .00000001
Ordinates (y-coordinates) are specified to the nearest .00000001
Planar coordinates are specified in Meters
The horizontal datum used is North American Datum of 1927.
The ellipsoid used is Clarke 1866.
The semi-major axis of the ellipsoid used is 6378206.4.
The flattening of the ellipsoid used is 1/294.9786982.
The line features are: map boundary, photointerpreted contact, and fault
| Value | Definition |
|---|---|
| N | The feature IS NOT covered by an overlying map unit. |
| Y | The feature IS covered by an overlying map unit. |
| Value | Definition |
|---|---|
| certain | Indicates that the author has sufficient observational and/or other supporting data to be reasonably confident in the scientific credibility of the interpretation of the feature. The level of certainty is specific to the map scale. |
| Value | Definition |
|---|---|
| certain | Indicates that the author has sufficient observational and/or other supporting data to be reasonably confident in the scientific credibility of the interpretation of the feature. The level of certainty is specific to the map scale. |
| Value | Definition |
|---|---|
| NULL | A value of -9 indicates that this measure is not available. |
| Formal codeset | |
|---|---|
| Codeset Name: | FGDC Digital Cartographic Standard for Geologic Map Symbolization; Appendix A. Geologic map symbols, colors, and patterns, "REF NO" field |
| Codeset Source: | Federal Geographic Data Committee [prepared for the Federal Geographic Data Committee by the U.S. Geological Survey], 2006, FGDC Digital Cartographic Standard for Geologic Map Symbolization: Reston, Va., Federal Geographic Data Committee Document Number FGDC-STD-013-2006, 290 p., 2 plates. |
The types of features are: "borehole" and "erratic"
Generic example of a sample identifier: YYYYAAA9999X: YY or YYYY= year, AAA=geologist's initials (one to three characters), 9999=unique station number, X= optional alpha character which indicates that multiple samples were collected at a given location or that multiple observations were recorded in the project database.
| Value | Definition |
|---|---|
| Qd | UNDIFFERENTIATED GLACIAL DRIFT--Heterogeneous, nonstratified, polymictic pebble-cobble gravel with some sand and silt and few to numerous subangular to subrounded boulders deposited by glacial ice and locally reworked by meltwater washing and associated mass-movement processes; forms thick deposits on lower bedrock walls of glaciated valleys; kettle fillings of interlayered peat, sand, and silt may be several meters thick |
| b | UNDIFFERENTIATED BEDROCK--Exposed undifferentiated bedrock |
| Formal codeset | |
|---|---|
| Codeset Name: | FGDC Digital Cartographic Standard for Geologic Map Symbolization; Appendix A. Geologic map symbols, colors, and patterns, "REF NO" field |
| Codeset Source: | Federal Geographic Data Committee [prepared for the Federal Geographic Data Committee by the U.S. Geological Survey], 2006, FGDC Digital Cartographic Standard for Geologic Map Symbolization: Reston, Va., Federal Geographic Data Committee Document Number FGDC-STD-013-2006, 290 p., 2 plates. |
free text that is intended to display adjacent to the label point on the map
| Value | Definition |
|---|---|
| NULL | Zero (0) values indicate that the point is intended to plot at all scales |
| Value | Definition |
|---|---|
| NULL | A value of -9 indicates that this measure is not available. |
The notes indicate the source of the feature interpretation or provide more information about the feature: "USGS borehole, modified from Odum and others (1986)", "Granite erratic", "Granite boulder in QTvc", "Stage 4(?) morainal remnant", "Cluster of granitic erratics", "Erratics near head of North Capps Creek", "Glacially faceted volcanic erratic", "Stage 4 erratics displaced downslope", "Granitic erratic, Stage 6", "Granitic erratic on Stage 6 moraine", "Weathered Stage 6 erratic", "Frost jacked volcanic clast on Stage 6 moraine", "Volcanic erratic on Stage 4 drumlin", "Highest granitic blocks, east side volcanic plateau", "Weathered surface of granitic erratic", "Glacier-scoured granite", "Stage 4(?) granite erratic", "Stage 4(?) glacial remnants", "Granitic erratic", "Metasedimentary erratic", "Grus remnants of granite erratic(?)", "Granite clast", "Small cluster of granite clasts", "Igneous erratic", "Granite erratic on volcanic plateau", "Granite erratic on Stage 6 moraine", "Granite erratics on Stage 6 moraine", "Highest Stage 4 granite erratics", "Highest Stage 4 granite erratic", "Stage 4 granite erratics", and "Stage 4 granite erratic"
The samples were analyzed by: " and "radiocarbon"
Generic example of a sample identifier: YYYYAAA9999X: YY or YYYY= year, AAA=geologist's initials (one to three characters), 9999=unique station number, X= optional alpha character which indicates that multiple samples were collected at a given location or that multiple observations were recorded in the project database. In some cases the station identifier may not follow this pattern.
| Value | Definition |
|---|---|
| Qda | VOLCANIC AVALANCHE DEPOSITS--Debris avalanche deposit catastrophically emplaced during major mid-Holocene sector collapse on southern flank of Mount Spurr volcanic complex; four recognized facies include (1) blocks, rubble schlieren, and coarse, angular avalanche debris; (2) altered blocks with little interstitial matrix and outcrop-scale block-against-block texture; (3) a mixed facies of block-cored hummocks surrounded by granular matrix sediments, and (4) poorly sorted, granular, matrix-supported volcanic debris, sand, silt, and clay that grade downvalley into a clay-rich lahar deposit (Waythomas, 2001, 2007). |
| Qdns | DRIFT OF SKILAK STADE--Morainal deposits of Skilak stade of Naptowne glaciation, including Congahbuna Lake and Denslow Lake moraines of Schmoll and Yehle (1987) |
| Qdnk | DRIFT OF KILLEY STADE--Morainal deposits of Killey stade of Naptowne glaciation, including Nikolai, 730 lake, and Threemile Creek moraines of Schmoll and Yehle (1987) |
| Qge | GLACIOESTUARINE DEPOSITS--Glacioestuarine sediments in Granite Point area sediments (Kaloa sediments of Schmoll and others, 1984) correlated with the Bootlegger Cove Formation (Reger, 2009) |
| Formal codeset | |
|---|---|
| Codeset Name: | FGDC Digital Cartographic Standard for Geologic Map Symbolization; Appendix A. Geologic map symbols, colors, and patterns, "REF NO" field |
| Codeset Source: | Federal Geographic Data Committee [prepared for the Federal Geographic Data Committee by the U.S. Geological Survey], 2006, FGDC Digital Cartographic Standard for Geologic Map Symbolization: Reston, Va., Federal Geographic Data Committee Document Number FGDC-STD-013-2006, 290 p., 2 plates. |
free text that is intended to display adjacent to the label point on the map
free text used to provide lab sample numbers or other means of identifying the sample
free text description of the sample; transcribed from geologists' field notes
| Value | Definition |
|---|---|
| NULL | Zero (0) values indicate that the point is intended to plot at all scales |
| Value | Definition |
|---|---|
| NULL | A value of -9 indicates that this measure is not available. |
| Range of values | |
|---|---|
| Minimum: | 3540 |
| Maximum: | 14350 |
| Units: | MA (million years ago) |
| Range of values | |
|---|---|
| Minimum: | 50 |
| Maximum: | 200 |
| Units: | MA (million years ago) |
| Range of values | |
|---|---|
| Minimum: | 50 |
| Maximum: | 200 |
| Units: | Ma (million years ago) |
| Value | Definition |
|---|---|
| radiocarbon years before present (RC yr B.P.) | radiocarbon years before present |
The notes indicate the source of the feature interpretation: "Minimum age for Holocene advance of Capps Glacier; Yehle and others (1983b locality A)", "Age of massive debris avalanche deposit and associated lahar; Waythomas (2006? table 1)", "Minimum age for retreat of ice from lateral moraine of Capps Glacier; Yehle and others (1983a locality A)", "Distant minimum age for Denslow Lake advance; Schmoll and Yehle (1987 coal exploration pit 1)", "Minimum age of Nikolai moraine; This study; calibrated age 14170-13230 yr B.P.", "Minimum age of Kaloa glacioestuarine section; Haeussler and others (2000 table 2) Reger (2009); calibrated age 14492-14136 yr B.P.", "Minimum age of Nikolai moraine; This study; calibrated age 14940-14230 yr B.P.", "Minimum age for Denslow Lake advance; Schmoll and Yehle (1987 sample x in figure 5 cross section C-C)", "Minimum age of Tyonek fan; This study; calibrated age 16880-16570 yr B.P.", and "Dates BCF in lower Beluga River area; Schmoll and Yehle (1983 locality B; 1986 locality B5) Schmoll and others (1984 locality B5)"
| Value | Definition |
|---|---|
| Hd | MODERN DRIFT--Drift of very recent age; mapped in areas where satellite imagery shows that glacier ice has retreated since 1978 aerial photography |
| Qab | ABANDONED-FLOODPLAIN ALLUVIUM--Alluvium of abandoned floodplain of Chakachatna River |
| Qac | ABANDONED-CHANNEL ALLUVIUM--Undifferentiated late Pleistocene to Holocene abandoned-channel deposits; includes sand and gravel deposited in channels formed by diversion of the Beluga River along margins of Threemile Creek moraine deposited by massive glacier lobe from lower Susitna River valley and ice-marginal and proglacial outwash related to 730 lake and Nikolai lateral and terminal moraines during Killey stade, granular outwash derived from the Denslow Lake terminal moraine during the Skilak stade, and sand and gravel deltas deposited in slackwaters of Beluga River jokulhlaups in lower valleys of Scarp and Bishop creeks; overlies varved clays near confluence of Bishop and Scarp creeks with Beluga River |
| Qal | UNDIFFERENTIATED ALLUVIUM--Alluvium of active, inactive, and abandoned floodplains; well-sorted and well-stratified polymictic pebble gravel, sand, and silt comprising channel and overbank deposits of major drainages; includes lahar deposits in upper Chakachatna River drainage |
| Qat | STREAM-TERRACE ALLUVIUM--Alluvium of stream terraces; massive to well-sorted, polymictic pebble gravel with some sand and scattered to numerous subrounded to sub-angular cobbles and boulders; no longer subject to flooding; includes lahar deposits and alluvium of jokulhlaups in upper Chakachatna River drainage and jokulhlaup deposits in Beluga River drainage |
| Qc | UNDIFFERENTIATED COLLUVIUM--Blankets, aprons, cones, and fans of heterogeneously mixed angular to subangular rock fragments, gravel, sand, and silt deposited by complex, gravity-driven mass movements involving sliding, flowing, and frost creep of weathered bedrock and modified glacial drift; cobbles and boulders are scattered to numerous; on lower headwalls of cirques and upper walls of glaciated valleys includes talus cones, incipient rock glaciers, and steep fans built by rockfalls and snow avalanches |
| Qcf | MIXED COLLUVIUM AND ALLUVIUM--Primarily fan-shaped or elongate, massive to poorly stratified, generally inorganic silt mixed with sandy, angular to subangular pebble gravels derived from weathering of Tertiary bedrock and laid down by debris-flow deposits and torrential water flows during brief, intense storms; colluviation is greater than alluviation |
| Qcl | LANDSLIDE DEPOSITS--Massive, extensive slides and flows produced by widespread, retrogressive failures of Tertiary sedimentary bedrock; composed of large blocks of Tyonek Formation mixed with glacial and colluvial diamictons; surface features include sag ponds, prominent marginal scarps, wrinkle ridges, rotated slump blocks and sharp, multi-lobate toes associated with terminal bulges |
| Qd | UNDIFFERENTIATED GLACIAL DRIFT--Heterogeneous, nonstratified, polymictic pebble-cobble gravel with some sand and silt and few to numerous subangular to subrounded boulders deposited by glacial ice and locally reworked by meltwater washing and associated mass-movement processes; forms thick deposits on lower bedrock walls of glaciated valleys; kettle fillings of interlayered peat, sand, and silt may be several meters thick |
| Qda | VOLCANIC AVALANCHE DEPOSITS--Debris avalanche deposit catastrophically emplaced during major mid-Holocene sector collapse on southern flank of Mount Spurr volcanic complex; four recognized facies include (1) blocks, rubble schlieren, and coarse, angular avalanche debris; (2) altered blocks with little interstitial matrix and outcrop-scale block-against-block texture; (3) a mixed facies of block-cored hummocks surrounded by granular matrix sediments, and (4) poorly sorted, granular, matrix-supported volcanic debris, sand, silt, and clay that grade downvalley into a clay-rich lahar deposit (Waythomas, 2001, 2007). |
| Qdn | DRIFT OF NAPTOWNE GLACIATION--Undifferentiated morainal deposits of Naptowne glaciation of late Wisconsin (MIS 2) age |
| Qdne | DRIFT OF ELMENDORF STADE--Morainal deposits of Elmendorf stade of Naptowne glaciation, including Carlson Lake moraine |
| Qdnk | DRIFT OF KILLEY STADE--Morainal deposits of Killey stade of Naptowne glaciation, including Nikolai, 730 lake, and Threemile Creek moraines of Schmoll and Yehle (1987) |
| Qdnm | DRIFT OF MOOSEHORN STADE--Morainal deposits of Moosehorn stade of Naptowne glaciation, including 1405 and 810 lakes moraines of Schmoll and Yehle (1987) |
| Qdns | DRIFT OF SKILAK STADE--Morainal deposits of Skilak stade of Naptowne glaciation, including Congahbuna Lake and Denslow Lake moraines of Schmoll and Yehle (1987) |
| QdpI | PRE-NAPTOWNE DRIFT--Blueberry Hill drift sheet of pre-penultimate pre-Naptowne glaciation deposited by ice from the Chakachatna-McArthur Embayment, in the Lone Ridge area |
| QdpII | PRE-NAPTOWNE DRIFT--Upper Chuitna moraines of penultimate pre-Naptowne glaciation deposited by ice from the Capps Glacier corridor |
| Qes | DUNE SAND--Dune sand on low terrace of McArthur River |
| Qfd | DELTA DEPOSITS--Fine-grained prograding delta apron of Chakachatna-McArthur River drainage; inorganic silt and clay |
| Qff | EXPANSION-FAN DEPOSITS--Alluvium, debris flows, and lahar deposits of large expansion fan built in the Chakachatna-McArthur Embayment by breakout floods caused by breaching of massive debris avalanche that blocked Chakachatna River during mid-Holocene (Waythomas, 2001), breaching of smaller late Holocene lahars (Meyer and Trabant, 1995), and episodic outbursts of Chakachamna Lake, which was dammed by advances of Barrier Glacier; includes the large Beluga expansion fan deposited by Beluga River jokulhlaups late in the Killey stade. |
| Qfo | OUTWASH DEPOSITS--Outwash of Alaskan glaciation of Holocene age; massive to well-sorted, polymictic pebble gravel with some sand; scattered to numerous subrounded to subangular cobble and boulders proximal to former ice limits; in Chakachatna River valley includes clay-rich lahar deposits related to massive debris avalanche resulting from mid-Holocene sector collapse of Mt. Spurr (Waythomas, 2007) |
| Qfp | FAN GRAVELS--Granular fans of Killey and Skilak stades near Tyonek and lower Beluga River that are pitted by numerous kettle lakes resulting from fan deposition over stagnant ice related to Threemile Creek moraine; Tyonek outwash fan composed chiefly of sandy pebble gravel with scattered thin cobble beds overlying diamicton with scattered cobble and boulder dropstones; kettle fillings up to 4.7 m thick of thin to massive peat interlayered with thin beds of silt, sand, and tephras; river bluff through proximal zone of Beluga expansion fan exposes boulders overlying glacial diamicton |
| Qge | GLACIOESTUARINE DEPOSITS--Glacioestuarine sediments in Granite Point area sediments (Kaloa sediments of Schmoll and others, 1984) correlated with the Bootlegger Cove Formation (Reger, 2009) |
| Qhl | LAHAR DEPOSITS--Lahar deposits of middle to late Holocene age, including poorly sorted, nonstratified, bouldery gravel with sand and silt matrix and volcanic blocks up to 10 m diameter proximal to Mt. Spurr volcanic complex; transformed into fine-grained lahar-runout deposits along Chakachatna River and Straight Creek (Meyer and Trabant, 1995; Waythomas, 2001, 2007; Waythomas and Nye, 2002) |
| Ql | LAKE DEPOSITS--Lake sediments; impounded by massive Chakachatna River debris avalanche and Holocene advance of Straight Creek glacier |
| Qmb | BEACH DEPOSITS--Cobble-pebble gravels and sand |
| Qmr | BEACH-RIDGE DEPOSITS--Complex of gravel ridges separated by fine-grained trough fills |
| Qmt | TIDAL DEPOSITS--Tidal-flat sediments; mostly flocculated clays |
| Qs | SWAMP DEPOSITS--Organic swamp deposits; fibrous and locally woody peat interlayered with thin beds of organic silt, sand, and tephras deposited in lowlands; underlain by Bootlegger Cove Formation beneath coastal plain between Beluga River and Tyonek |
| Qv | UNDIFFERENTIATED VOLCANIC DEPOSITS--Undifferentiated volcanic deposits and rock of Quaternary age |
| Qvc | VOLCANICLASTIC PLATEAU DEPOSITS--Volcaniclastic complex of volcanic plateau consisting of crudely bedded conglomeratic to sandy to muddy volcanogenic debris and hyper-concentrated flows (Herriott and others, 2014); upper 1-6 m composed of very coarse sand derived from volcanic cinders reworked by wind, local meltwater, and spring flows and overlain by up to 2 m of loess composed primarily of Holocene tephras |
| Qvci | VOLCANICLASTIC Plateau Deposits Overridden by Ice--Volcaniclastic complex of Quaternary volcanic plateau that has been overridden by glacial ice |
| Qve | UNDIFFERENTIATED EOLIAN DEPOSITS--Mixed primary and reworked eolian sand and silt of volcanic compositions with thin tephras; surface thought to be channeled by glacial meltwater or snow melt (C. Waythomas, 5/22/2015 written commun.) |
| b | UNDIFFERENTIATED BEDROCK--Exposed undifferentiated bedrock |
| b' | THINLY COVERED BEDROCK--Undifferentiated bedrock overlain by thin, probably discontinuous cover of colluvium and glacial drift |
| b'(QdpI) | PRE-NAPTOWNE DRIFT--Thin and discontinuous cover over bedrock of Blueberry Hill deposits of pre-penultimate pre-Naptowne glaciation deposited by ice from the Chakachatna-McArthur Embayment, in the Lone Ridge area |
| Value | Definition |
|---|---|
| certain | Indicates that the author has sufficient observational and/or other supporting data to be reasonably confident in the scientific credibility of the interpretation of the feature. The level of certainty is specific to the map scale. |
| questionable | The interpretation of the feature at the mapped scale fits the overall proposed geologic model but the extent and/or classification is questionable or uncertain due to insufficient observations and/or supporting data. |
| Value | Definition |
|---|---|
| NULL | not applicable |
| Formal codeset | |
|---|---|
| Codeset Name: | FGDCGeoAge font |
| Codeset Source: | Federal Geographic Data Committee [prepared for the Federal Geographic Data Committee by the U.S. Geological Survey], 2006, FGDC Digital Cartographic Standard for Geologic Map Symbolization: Reston, Va., Federal Geographic Data Committee Document Number FGDC-STD-013-2006, 290 p., 2 plates. |
| Value | Definition |
|---|---|
| 0003 | CMYK value - C:0%, M:0%, Y:0%, K:30% |
| 4050 | CMYK value - C:40%, M:0%, Y:50%, K:0% |
| 0000 | CMYK value - C:0%, M:0%, Y:0%, K:0% |
| 0040 | CMYK value - C:0%, M:0%, Y:40%, K:0% |
| 00X0 | CMYK value - C:0%, M:0%, Y:100%, K:0% |
| 0020 | CMYK value - C:0%, M:0%, Y:20%, K:0% |
| 0060 | CMYK value - C:0%, M:0%, Y:60%, K:0% |
| A4X0 | CMYK value - C:8%, M:40%, Y:100%, K:0% |
| A370 | CMYK value - C:8%, M:30%, Y:70%, K:0% |
| 0A30 | CMYK value - C:0%, M:8%, Y:30%, K:0% |
| 10A0 | CMYK value - C:13%, M:0%, Y:8%, K:0% |
| 0A00 | CMYK value - C:0%, M:8%, Y:0%, K:0% |
| 50X0 | CMYK value - C:50%, M:0%, Y:100%, K:0% |
| 3070 | CMYK value - C:30%, M:0%, Y:70%, K:0% |
| A030 | CMYK value - C:8%, M:0%, Y:30%, K:0% |
| 1070 | CMYK value - C:13%, M:0%, Y:70%, K:0% |
| 2040 | CMYK value - C:20%, M:0%, Y:40%, K:0% |
| 6230 | CMYK value - C:60%, M:20%, Y:30%, K:0% |
| 4A20 | CMYK value - C:40%, M:8%, Y:20%, K:0% |
| 2470 | CMYK value - C:20%, M:40%, Y:70%, K:0% |
| 0350 | CMYK value - C:0%, M:30%, Y:50%, K:0% |
| A330 | CMYK value - C:8%, M:30%, Y:30%, K:0% |
| 0440 | CMYK value - C:0%, M:40%, Y:40%, K:0% |
| 0A70 | CMYK value - C:0%, M:8%, Y:70%, K:0% |
| 70A0 | CMYK value - C:70%, M:0%, Y:8%, K:0% |
| 32X0 | CMYK value - C:30%, M:20%, Y:100%, K:0% |
| 0001 | CMYK value - C:0%, M:0%, Y:0%, K:13% |
| A600 | CMYK value - C:8%, M:60%, Y:0%, K:0% |
| 3030 | CMYK value - C:30%, M:0%, Y:30%, K:0% |
| 7A20 | CMYK value - C:70%, M:8%, Y:20%, K:0% |
| 5000 | CMYK value - C:50%, M:0%, Y:0%, K:0% |
| 3000 | CMYK value - C:30%, M:0%, Y:0%, K:0% |
| 72A0 | CMYK value - C:70%, M:20%, Y:8%, K:0% |
| 0530 | CMYK value - C:0%, M:50%, Y:30%, K:0% |
| 0200 | CMYK value - C:0%, M:20%, Y:0%, K:0% |
| 0600 | CMYK value - C:0%, M:60%, Y:0%, K:0% |
| 0400 | CMYK value - C:0%, M:40%, Y:0%, K:0% |
The notes indicate the basis of the feature interpretation: " and "Pattern 116M"
We worked as members of a team of geologists on the staffs of the Alaska Division of Geological & Geophysical Surveys and Alaska Division of Oil and Gas, including, in alphabetical order: Paul Decker, Brent Elliott, Larry Freeman, Bob Gillis, Laura (Silliphant) Gregersen, Ken Helmold, Trystan Herriott, Dave LePain, Dave Mauel, and Shaun Peterson. Dave LePain and Bob Gillis both provided effective leadership. Excellent assistance in the field was provided by interns Kandace Krejci, Jake Mongrain, Keane Richards, and Garrett Speeter. Our U.S. Geological Survey colleagues Tom Ager, Andy Calvert, Michelle Coombs, and Rick Stanley kindly provided insightful information related to their investigations that was very helpful to ours. Expertise provided by our Purdue University colleagues Ken Ridgway and Emily Finzel was essential to our understanding of the geologic framework and tectonics of the study area. Support by the Cottonwood Camp staff ensured that we were well fed, showered frequently, slept dry, and were therefore willing and able to venture into the field when the weather allowed. When we could fly, helicopter pilots Ray Hodges, Tom Ratledge, Chuck Redd, and Joe Trudo safely landed us where we needed to go and brought us intact back to base camp at the end of the day. We greatly appreciated permission to work in lands owned by Cook Inlet Region Incorporated (CIRI), Tyonek Native Corporation, and Tyonek Village Corporation. We particularly appreciate constructive technical reviews provided by Chris Waythomas (USGS) and Trent Hubbard (DGGS), which helped clarify this report. This publication was funded by the State of Alaska and the National Cooperative Geologic Mapping Program's STATEMAP program (awards G09AC00177 and G10AC00321), administered by the U.S. Geological Survey.
(907)451-5020 (voice)
dggsgis@alaska.gov
The 2,220 square km Tyonek map area near the northwestern shore of upper Cook Inlet contains important petroleum, coal, aggregate, geothermal, and timber resources. This report provides basic surficial-geologic information useful for exploiting those resources and planning future utility corridor developments.
Herriott, T.M., Nye, C.J., Reger, R.D., Wartes, M.A., LePain, D.L., and Gillis, R.J., 2014, Geologic context, age constraints, and sedimentology of a Pleistocene volcaniclastic succession near Mount Spurr volcano, south-central Alaska: Report of Investigation RI 2014-2, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.Online Links:
Keith, T.E.C., 1995, The 1992 eruptions of Crater Peak vent, Mount Spurr Volcano, Alaska: Bulletin B 2139, U.S. Geological Survey, United States.Online Links:
Reger, R.D., 2009, Reinterpretation of the Kaloa deposits near Granite Point, northwestern Cook Inlet, Alaska: Preliminary Interpretive Report PIR 2009-2, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.Online Links:
Schmoll, H.R., and Yehle, L.A., 1987, Surficial geologic map of the northwestern quarter of the Tyonek A-4 Quadrangle, south-central Alaska: Miscellaneous Field Studies Map MF 1934, U.S. Geological Survey, United States.Online Links:
Waythomas, C.F., 2007, Mid-Holocene sector collapse at Mount Spurr volcano, south-central Alaska: Professional Paper P 1739-C, U.S. Geological Survey, United States.Online Links:
Waythomas, C.F., and Nye, C.J., 2001, Preliminary volcano-hazard assessment for Mount Spurr Volcano, Alaska: Open-File Report OF 2001-482, U.S. Geological Survey, United States.Online Links:
Data sources used in this process:
Reger, R.D., 2009, Reinterpretation of the Kaloa deposits near Granite Point, northwestern Cook Inlet, Alaska: Preliminary Interpretive Report PIR 2009-2, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.Online Links:
Koehler, R.D., and Reger, R.D., 2011, Reconnaissance evaluation of the Lake Clark fault, Tyonek area, Alaska: Preliminary Interpretive Report PIR 2011-1, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.Online Links:
Certainty in identification of the map units varies due to the scale and interpretive nature of the mapping. The geologic unit interpretations and boundaries presented in this map result from interpretation of false-color infrared aerial photographs, investigative traverses throughout the map area, and aerial reconnaissance via helicopter. Information from previous geologic reports and maps was also incorporated into this publication. The air-photo interpretations were adjusted as needed to be consistent with exposures identified by field geologists. Soil colors were described using the Munsell soil color charts. The Wentworth scale was used for grain size classification. Soil horizon descriptions in the map area used the U.S. Soil Conservation Service soil taxonomy (Soil Survey Staff, 1975). Sediment samples were collected for sieve analysis and radiocarbon age dating. Analytical data described above were utilized in developing the geologic interpretations presented in this report. Per NCGMP09 (USGS National Cooperative Geologic Mapping Program - Draft Standard Format for Digital Publication of Geologic Maps) specifications, the authors have assigned a confidence value to each polygon and line segment to indicate their degree of confidence in the positioning and identification of the element at the mapped scale. To check attribute accuracy of the digital files we visually compared the original compilation against test plots of the files and corrected discrepancies between the digital geospatial dataset and the original analog as needed. The geologic interpretations presented in this report have undergone technical editing and two technical reviews by geologists familiar with the subject of the report and the geology of the map area. We incorporated the reviewers' suggestions into the final draft when deemed appropriate.
Location data for samples were collected with handheld GPS. Mappers recorded observations on 1:65,000 scale (false) color-infrared aerial photographs and 1:63,360 scale USGS topographic base maps. The authors believe the total horizontal accuracy of directly observed mapped geologic contacts is on the order of 25 m or better, with somewhat lesser accuracy expected in areas of rugged relief. Per NCGMP09 specifications, the authors have assigned a confidence value to each polygon, line, or point to indicate their degree of confidence in the positioning and identification of the element at the mapped scale. Waterlines and waterbody polygons were entirely derived from topographic base maps, consequently it is possible that the mapped location and extent of these features may differ from modern ground conditions. Glacier ice extents were updated using 1999-2003 Landsat satellite imagery.
This report and digital dataset provides information about geologic features that can be identified or interpreted at a scale of 1:50,000. Relative to pre-existing mapping, it offers an improved understanding of the geology, glacial history, and geologic hazard of the map area. Uncertainties in geologic unit interpretation are noted on the map and in the GIS files. Additional work would be required to fully resolve uncertainties in our interpretations.
Polygon topology was implemented per NCGMP09 specifications (polygons must not overlap, polygons must not have gaps, boundaries must be overlain by lines in ContactsAndFaults). All polygon features were topologically validated using ArcGIS for Desktop prior to export to shapefile format.
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- Access_Constraints:
- This report, map, and/or dataset is available directly from the State of Alaska, Department of Natural Resources, Division of Geological & Geophysical Surveys (see contact information below).
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- Any hard copies or published datasets utilizing these datasets shall clearly indicate their source. If the user has modified the data in any way, the user is obligated to describe the types of modifications the user has made. The user specifically agrees not to misrepresent these datasets, nor to imply that changes made by the user were approved by the State of Alaska, Department of Natural Resources, Division of Geological & Geophysical Surveys. The State of Alaska makes no express or implied warranties (including warranties for merchantability and fitness) with respect to the character, functions, or capabilities of the electronic data or products or their appropriateness for any user's purposes. In no event will the State of Alaska be liable for any incidental, indirect, special, consequential, or other damages suffered by the user or any other person or entity whether from the use of the electronic services or products or any failure thereof or otherwise. In no event will the State of Alaska's liability to the Requestor or anyone else exceed the fee paid for the electronic service or product.
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RI 2015-7
The State of Alaska makes no expressed or implied warranties (including warranties for merchantability and fitness) with respect to the character, functions, or capabilities of the electronic data or products or their appropriateness for any user's purposes. In no event will the State of Alaska be liable for any incidental, indirect, special, consequential, or other damages suffered by the user or any other person or entity whether from the use of the electronic services or products or any failure thereof or otherwise. In no event will the State of Alaska's liability to the Requestor or anyone else exceed the fee paid for the electronic service or product.
DGGS publications are available as free online downloads or you may purchase paper hard-copies or digital files on CD/DVD or other digital storage media by mail, phone, fax, or email from the DGGS Fairbanks office. To purchase this or other printed reports and maps, contact DGGS by phone (907-451-5020), e-mail (dggspubs@alaska.gov), or fax (907-451-5050). Payment accepted: Cash, check, money order, VISA, or MasterCard. Turnaround time is 1-2 weeks unless special arrangements are made and an express fee is paid. Shipping charge will be the actual cost of postage and will be added to the total amount due. Contact us for the exact shipping amount.
| Data format: | Shapefiles |
|---|---|
| Network links: |
<http://dx.doi.org/10.14509/29471> |
(907)451-5020 (voice)