QUATERNARY GEOLOGY of the FOSSTON 30' X 60' QUADRANGLE, NORTHWEST MINNESOTA # # Geological Survey in St

MINNESOTA GEOLOGICAL SURVEY Harvey Thorleifson, Director Prepared and Published with the Support of THE U.S. GEOLOGICAL SURVEY AS PART OF THE 2006 STATE GEOLOGIC MAPPING PROGRAM ELEMENT (STATEMAP) OF THE NATIONAL GEOLOGIC MAPPING PROGRAM MISCELLANEOUS MAP SERIES �� MAP M-177 �� Quaternary Geology, Fosston Quadrangle �� INTRODUCTION Qlg Loam, pebbly �� This plate presents a lithostratigraphic interpretation of the surface and subsurface geology (shown only on cross section)—Unsorted; unbedded; contains inclusions of sand and gravel; commonly contains cobbles and boulders; as �� of the Fosston 30' x 60' quadrangle (Fig. 1). Lithostratigraphic units are defined by sediment MAP SYMBOLS �� much as 70 feet (21 meters) thick, but generally 15 to 30 feet (5 to 9 meters) �� type (lithology) and stratigraphic position. The lithostratigraphic map shows areas of surface �� thick; where overlain by the Upper Red Lake Falls Formation, this unit was Geologic contacts �� exposure of these units and the cross section shows their interpreted spacial relationship at deposited by glacial ice on an ice-cored, glaciated landscape and subsequently Approximate �� depth. —Judged to be within 0.25 mile (0.4 kilometer) �� eroded by glacial ice (west end of the cross section); where not overlain by of the true boundary along most of its length. �� The basic data used for the lithologic interpretation of the map area, except for the Red Lake �� the Upper Red Lake Falls Formation, this unit was deposited on an ice-cored, Inferred —Judged to be between 0.25 mile (0.4 kilometer) and �� Indian Reservation, consists of: 1. Interpretation of aerial photography; 2. Field observations; 3. �� glaciated landscape or stagnant ice; water-saturated sediment flowed in response 0.5 mile (0.8 kilometer) from the true boundary along most �� Interpretation of sample data contained in a regional database, QBASE (Minnesota Geological �� to gravity and was modified by the presence of standing and flowing water; Survey, 2007b); and 4. General soil maps (Agricultural Experiment Station, 1980; U.S. Department of its length. �� glacier-eroded glacial sediment. �� Speculated —Judged likely to be more than 0.5 mile (0.8 � �� of Agriculture, 1997a, b, c, 2003, 2004, 2005). Qlw Loam, pebbly —Unsorted; unbedded; contains abundant cobbles and boulders; as kilometer) from the true boundary. �� The basic data used for the stratigraphic interpretation of the map area, except for the Red �� much as 50 feet (15 meters) thick, but generally 15 to 30 feet (5 to 9 meters) Lake Indian Reservation, consists of: 1. Interpretation of sample data contained in a regional Beach ridge —Established from aerial photographs; line indicates �� thick; unit has a flat to undulating surface commonly with a veneer of sand and database, QBASE (Minnesota Geological Survey, 2007b); 2. Previous work in the Red River valley the crest of the ridge; interpreted to be beach ridges or off �� gravel; generally less than 6 feet (2 meters) of relief; deposited by glacial ice �� shore bars deposited along the margin of Glacial Lake Agassiz; �� (Harris, 1973, 1975, 1987, 1995, 1999, 2003, 2006a, b; Harris and others, 1974, 1996; Moran �� on an ice-cored, glaciated landscape; eroded by running water; �� and others, 1976; Arndt, 1977; Harris and Luther, 1991; Thorleifson and others, 2005); and 3. discernible on topographic maps and on the ground. low-relief glacial sediment. water-eroded, �� Interpretation of water-well data contained in the Minnesota Geological Survey's County Well Channel scour —Established from aerial photographs; a line marks �� Qlo Sand and gravel �� Index (Minnesota Geological Survey, 2007a). The geology presented on the Red Lake Indian —Moderately sorted; crossbedded to flatbedded; as much as the scour, the arrow indicates probable direction of water �� 50 feet (15 meters) thick; sand where stippled; �� Reservation is based on interpretation of aerial photography, a general soil map (Agricultural flow; interpreted to be anastomosing stream channels eroded �� uncollapsed glacial outwash �� associated with the lower Red Lake Falls formation. �� Experiment Station, 1980), and regional geology. during episodes of overland flow; generally not apparent on �� Qlc Sand and gravel —Moderately sorted; disturbed crossbedded to flatbedded; topographic maps or on the ground. �� Quaternary sediments were deposited in the map area by glacial ice, rivers, the wind, and �� gravity. Figure 1 shows the location of the map area and regional glacial and lacustrine events as much as 50 feet (15 meters) thick; sand where stippled; Esker —Established from aerial photographs; line indicates the �� collapsed glacial influencing the area. The two ice margins shown on the lithostratigraphic map and Figure 1 outwash associated with the lower Red Lake Falls formation. crest of a sinuous ridge, located in collapsed glacial sediment; �� Qot Sand and silt �� mark stable positions of glacial ice that deposited the Upper Red Lake Falls Formation (ice —Moderately to poorly sorted; crossbedded to flatbedded; as much interpreted to mark the location of a stream channel (commonly �� margin 1 or Perley moraine) and the Lower Red Lake Falls Formation (ice margin 2 or Comstock as 10 feet (3 meters) thick overlying glacial sediment; overlying sand and gravel sand and gravel) that formed on top of, in, or under glacial �� moraine). They do not necessarily mark glacial maximums. where stippled; uncollapsed glacial outwash associated with the lower Red Lake ice; apparent on topographic maps, generally apparent on the �� Falls formation. ground. �� Cross section A–A' shows the generalized, schematic relationship of lithostratigraphic units �� in the subsurface of the map area based on available well control. Minor surface map units Upper Goose River group (Figs. 1, 3; Tables 1, 2) Sharp scarp �� —Established from aerial photographs; line indicates �� —Deposited by glacier ice as a result �� do not appear on the cross section. Stratigraphic data from four previously drilled test holes, of a readvance of the generally retreating Late Wisconsinan glacier in the Red the crest of the scarp and the hachures point downslope; easily �� N-1914, N-1915, McIntosh, and N-1920, were used to construct the cross section (Minnesota discernible on topographic maps and on the ground. �� River lowland. �� Geological Survey, 2007b). The locations of the test borings are shown on the surficial map Palimpsest channel St. Hilaire Formation —Pebbly clay-loam; unbedded; unsorted; columnar structure or —Established from aerial photographs; lines �� and in Figure 2. These four borings, ranging in depth from 75 to 155 feet (23 to 47 meters), weak vertical jointing is common in dry outcrops along the Red Lake River indicate the crests of the scarps; half-circles indicate the �� provided the only borehole stratigraphic control available; therefore, the cross section is highly in the Red Lake Falls area of Red Lake County; shale pebbles are common; downslope direction; half-circles are omitted within very �� generalized and units do not correspond with the map. narrow channels; interpreted to be a buried meltwater channel; �� contains lignite fragments; gray to very dark gray; calcareous; not present on Stratigraphic units were correlated between the control borings using available water wells the surface in the map area; generally apparent on topographic maps, may not be apparent �� glacial sediment (Harris, 1973, 1975, 1995, 1999, along the path of the cross section. Water wells within 1.0 mile (1.5 kilometers) of the cross 2003, 2006a, b; Harris and others, 1974, 1996; Moran and others, 1976; Arndt, on the ground. �� section are displayed in areas where there were abundant water wells. Water wells within 1.5 Ice margin �� 1977; Thorleifson and others, 2005). —Position established from aerial photographs, �� miles (2.5 kilometers) of the cross section are displayed in areas where there were fewer water Qsg Clay-loam, pebbly (shown only on cross section)—Unbedded; unsorted; contains topographic cross section, and analysis of sediment samples; wells. Because of the low density of water wells along the path of the cross section, both hachures point toward the glacier; interpreted to be the �� inclusions of sand and gravel; contains cobbles and boulders; as much as 70 feet �� located and unlocated water wells were used. Located water wells have had their reported (21 meters) thick, but generally 3 to 30 feet (1 to 9 meters) thick; deposited by approximate position of a glacial margin; may mark a glacial �� location verified; unlocated water wells have not.

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