# 054_Hughes_OF167_Landform_Category

DESCRIPTION:
Low hills: relief 100-500 ft. (30 to 160 m)


# 054_Hughes_OF167_Legends_Sheet1

NAME:
Hummocky, ridged glaciofluvial deposits (includes eskers and esker complexes)

LANDFORM_TOPOGRAPHY:
Hummocks and ridges, relief to 40 m Slope 5-15 degree

GROUND_ICE:
Typically no segregated ice in well drained sites, but segregated ice may be present in association with silt layers beneath depressions.

COMMENTS:
Offers good construction sites; major source of aggregate where material is gravel rather than sand.


LANDFORM_DRAINAGE_PATTERN:
Downslope seepage in shallow sub-parallel runnels

COMMENTS:
Potential subsidences on removal of vegetation typically less than 1 m ; potential for creep of active layer, especially in slope category2. Because of drainage by numerous sub-parallel runnels, roads or berms normal to slope direction require numerous culverts to avoid impoundment of surface water.


LANDFORM_TOPOGRAPHY:
Flat to very gently to gently sloping, in part with reticulate network of low ridges. Slope 0-2 degree Relief to 1 m

LANDFORM_DRAINAGE_PATTERN:
No organized drainage; water at surface throughout summer months

GROUND_ICE:
Commonly unfrozen to 2+m (see “Depth of Thaw” for respective zones) little data available on segregated ice content at greater depths.

COMMENTS:
Poor drainage, plus high compressibility and low strength of the material make it unsuitable for any type of construction.


SURFICIAL_DEPOSIT_MATERIAL:
Peat- typically sedge and woody sedge peat overlain by sphagnum peat

LANDFORM_TOPOGRAPHY:
Flat to very gently sloping, typically with numerous shallow steep-sided (2- 3 m) depressions occupied by lakes, ponds and bogs.

LANDFORM_DRAINAGE_PATTERN:
Depressions interconnected by seepage channels

GROUND_ICE:
Commonly up to 20 %, locally up to 60% segregated ice within peat; typically 30-100 cm, locally up to 3 m total thickness segregated ice in mineral soil immediately below peat. Peat in wet depressions commonly thawed to 1m+(Zones 1, 2) or unfrozen (Zones 2, 3)

COMMENTS:
Subsidence of up to 1 m common, and subsidence up to 3 m possible, when vegetation is removed; alternation of permanently frozen peat plateaus and thawed depressions and water bodies presents serious problems in construction of roads, pipelines, etc.; material highly compressible when thawed.


NAME:
Alluvial flood-plain of high energy streams

LANDFORM_TOPOGRAPHY:
Flood plain and low bordering terraces scarred by braided channels Slope 0-3 degree Relief to 2 m

LANDFORM_DRAINAGE_PATTERN:
Intermittent drainage through braided channels

GROUND_ICE:
Permafrost lacking in active unvegetated parts of floodplain; elsewhere cement ice only, except in silt veneer which commonly has 10 to 25 % segregated ice as thin (1 mm- 2 cm) seams

COMMENTS:
Subject to periodic flooding; constitutes potential reserve of gravel but extraction presents serious possibility of deleterious changes in stream course and down-stream changes in stream regimen.


NAME:
Organic veneer (mapped mainly as a secondary unit with tMp, tMv)

LANDFORM_TOPOGRAPHY:
Shallow channels, runnels and depressions; Slope 0-30degree Relief to 1 m

LANDFORM_DRAINAGE_PATTERN:
Surface seepage in channels, depressions

GROUND_ICE:
Organic veneer lies mainly within the active layer; (for ice in mineral soil below, see associated map unit).

COMMENTS:
Similar to fO; areas with mappable fOv component (+10%) should be avoided in construction of roads, pipelines, etc.


NAME:
Alluvial floodplain of low energy streams

LANDFORM_TOPOGRAPHY:
Flood plain and low bordering terraces commonly with meander scars. Slope 0-3 degree Relief to 1 m

LANDFORM_DRAINAGE_PATTERN:
No integrated drainage system; impeded by meander scroll ridges where present

GROUND_ICE:
Permafrost lacking in unvegetated part of floodplain; elsewhere 10 to 25 % segregated ice by volume as thin (1 mm- 2 cm) seams. Ice wedge in polygonal pattern (diameter of polygons 6- 25 m) common in Zone 2.

COMMENTS:
Subject to periodic flooding; melting of ice wedges produced polygonal network of depressions when vegetation is removed.


NAME:
Thermokarst alluvial floodplain (associated with low energy streams only)

LANDFORM_TOPOGRAPHY:
Level floodplain, in part with meander scars, and with numerous channels and thermokarst ponds. Slopes 0- 3 degree short steep slopes to 45 degree Relief to 5 m

LANDFORM_DRAINAGE_PATTERN:
Seepage to ponds and lakes, to adjacent streams by connection channels

GROUND_ICE:
20 to 50% segregated ice by vol. In upper 2-3 m (and probably to greater depth)

COMMENTS:
Thermokarst processes active around pond margins; melting of ice wedges produces polygonal network of depressions when vegetation is removed; subject to periodic flooding; highly unsuitable as construction sites.


LANDFORM_TOPOGRAPHY:
Level to gently sloping terrace, in part with shallow channels and steep scarps. Slope 0-3 degree, locally to 30 degree Relief to 5 m, greater at scarps

LANDFORM_DRAINAGE_PATTERN:
Surface drainage without integrated drainage system

GROUND_ICE:
Cement ice only except in silt veneer which commonly has 10 to 25% segregated ice as thin (1 mm- 2 cm) seams.

COMMENTS:
Offer good construction sites where silt veneer is thin; potential aggregate source.


SURFICIAL_DEPOSIT_MATERIAL:
Silt, fine-grained sand; veneer of eolian silt or sand (rare)

GROUND_ICE:
Commonly 10 to 25% segregated ice as thin (1mm-2cm) seams in upper 1-3m; at greater depth segregated ice to 40% by volume as reticulate network (in subjacent massive silts and clays) or as layers 2-5cm thick (in varved silts and clays); also thick tabular bodies of nearly pure ice; ice wedges as polygonal networks usually present (see comments for ground ice in si\g Atk unit).

COMMENTS:
Ground-ice data refer to the thermokarst alluvial terraces of Bell Basin (1161, P) where the terraces are underlain at depth by glaciolacustrine and/or non-glacial sediments; in map-area 1164 (E1/2) & 0, thermokarst alluvial terraces are underlain by silt 5 to 6 m thick in turn underlain by gravel; segregated ice as thin (1-2 cm) lenses in upper 1-3 m, or occasional thick tabular bodies at greater depth in silt; ice wedges as polygonal networks usually present; probably cement ice only in gravels.


NAME:
Thermokarst alluvial terrace of low energy streams


SURFICIAL_DEPOSIT_MATERIAL:
Highly variable silt, sand, gravel, peat

LANDFORM_TOPOGRAPHY:
Gently to moderately sloping fans and aprons Slopes 1-12 degree

LANDFORM_DRAINAGE_PATTERN:
One or more shifting streams usually present; downslope seepage in poorly defined runnels and considerable subsurface seepage in gravel fans

GROUND_ICE:
Highly variable; low in gravel, mod. to very high in silt (the more common case). Thin seams in upper 2-3 m; thick layers to 30+cm at depth. Ice content generally lower in coarser sediments at head of fan than in finer sediments at outer margin.

COMMENTS:
Fans composed of sand and gravel offer well-drained building sites, but sudden and damaging shifts of streams on the fans are common; fans with high silt content are unsuitable for construction. Fans of gravel, sand (rare) are good sources of aggregate; subsurface drainage in gravel fans may cause difficulties in utilization of borrow pits.


SURFICIAL_DEPOSIT_MATERIAL:
Colluvium derived from entire range of surficial deposits plus bedrock detritus

LANDFORM_TOPOGRAPHY:
Steeply sloping valley walls and scarps. Slope 12 to 45 degree Relief to 300 m

COMMENTS:
Active stream erosion, slumping, restrogressive-thaw flow slides, active-layer detachment slides common; irregularity of topography and slope instability present major problems for any kind of construction; see comments re map unit on which colluvium is developed.


SURFICIAL_DEPOSIT_MATERIAL:
Rock detritus, minor glacially transported material

LANDFORM_TOPOGRAPHY:
Veneer conforms to bedrock topography Hilly to mountainous Slopes to 45 degree

COMMENTS:
Sorted polygons, stone stripes, in part active, suggest cryoturbation; solifluction lobes on high slopes (elev. 800M+) of Richardson Mountains indicate active creep of colluvial veneer.


LANDFORM_TOPOGRAPHY:
Thin veneer or dune ridges within or adjacent to areas of Gp, GLp Slope to 20 degree Relief to 10 m

LANDFORM_DRAINAGE_PATTERN:
Mainly sub-surface seepage; no organized drainage

GROUND_ICE:
No data; probably cement ice only below active layer; segregated ice highly probable in subjacent glaciolacustrine silts where eolian deposits occur within areas of GLp.

COMMENTS:
Offer restricted well-drained sites within large areas of poorly drained units GLp, Glpk; subject to wind erosion when vegetation mat is removed. Gulleying commonly occurs upon removal of the vegetation mat in areas where eolian sand forms a thin veneer over ice-rich till or lacustrine sediments.


SURFICIAL_DEPOSIT_MATERIAL:
Glaciolacustrine silt and clay; discontinuous organic cover

LANDFORM_TOPOGRAPHY:
Flat to gently sloping Slope 0-2 degree Relief to 3 m

LANDFORM_DRAINAGE_PATTERN:
Surface seepage through fen-filled depressions

GROUND_ICE:
No data; should be treated as Lpk until data available.

COMMENTS:
Active-layer detachment slides, followed by development of retrogressive-thaw flow slides, common on colluvial slopes (Cx) developed on this unit (and on lesser areas of steep slopes not mapped as Cx), especially following fire or other disturbance of vegetation. Gulleying commonly results even on gentle slopes upon removal of vegetation due to combined hydraulic and thermal erosion and diruption of the drainage network. West of the Richardson Mountains this unit is underlain by unconsolidated basin-fill sediments. The subjacent non-glacial sediments in the lacustrine plains of the unglaciated area typically have a much lower ice content.


LANDFORM_TOPOGRAPHY:
Flat to gently sloping, numerous shallow thermokarst lakes and ponds Slope 0-5 degree Relief to 6 m

LANDFORM_DRAINAGE_PATTERN:
Seepage contripetal to ponds and lakes, intermittent seepage through fen-filled depressions between ponds and lakes

GROUND_ICE:
Commonly up to 10-25% segregated ice as thin (1mm-2cm) seams in upper 1-3 m; segregated ice as reticulate network to 40% by volume, or thick tabular bodies of nearly pure ice at greater depth.

COMMENTS:
Thermokarst processes active around pond margins; active-layer detachment slides followed by development of retrogressivethaw flow slides, common on colluvial slopes (Cx) developed on this unit (and on lesser areas of steep slope not mapped as Cx), especially following fire or order disturbance of vegetation. Gulleying is common even on gentle slopes upon removal of vegetation. West of the Richarson Mountains this unit is underlain by unconsoldiated basin-fill sediments. The subjacent non-glacial sediments in the lacustrine plains of the unglaciated area typically have a much lower ice content.


SURFICIAL_DEPOSIT_MATERIAL:
Glaciolacustrine silt and clay overlain by glaciofluvial sand with minor silt, rare fine gravel. Discontinuous organic cover

SURFICIAL_DEPOSIT_ESTIMATED_THICKNESS:
1-35+m sand, minor gravel 3-15+m silt and clay

GROUND_ICE:
No data; should be treated as GLpk until data available.

COMMENTS:
Active-layer detachment slides, followed by development of retrogressive-thaw flow slides, common on colluvial slopes (Cx) developed on this unit (and on lesser areas of steep slopes not mapped as Cx), especially following fire or other disturbance of vegetation. Rotataional slope failures common along banks of larger streams where sand and silt is thicker than 10 m. Gulleying is common even on gentle slopes upon removal of vegetation. The subjacent non-glacial sediments in the lacustrine plains plains of the unglaciated area typically have a such lower ice content.


LANDFORM_DRAINAGE_PATTERN:
Seepage contripetal to ponds and lakes, intermittent seepage along fen-filled depressions between ponds and lakes.

GROUND_ICE:
Commonly up to 10 to 25% segregated ice as thin (1mm-2cm) seams in upper 2-3m of sand, but massive segregated ice rare in the sand; very high ice content (to 75% by vol.) as reticulate network or thick tabular bodies in underlying silt and clay.

COMMENTS:
Thermokarst processes active around pond margins; active-layer detachment slides followed by development of retrogressive-thaw flow slides, common on colluvial slopes (Cx) developed on this unit (and on lesser areas of steep slope not mapped as Cx), especially following fire or other disturbance of vegetation. Rotational slope failures common along banks of larger streams where sand and silt is thicker than 10 m. Gulleying is common even on gentle slopes upon removal of vegetation. The subjecent non-glacial sediments in the lacustrine plains of the unglaciated area typically have a much lower ice content.


SURFICIAL_DEPOSIT_MATERIAL:
Sand, gravel, locally with veneer of eolian silt or sand

LANDFORM_TOPOGRAPHY:
Flat to gently sloping Slope 0-2 degree Relief to 5 m

GROUND_ICE:
Typically cement ice only, polygonal pattern on some areas of unit in Zones 0, 1 suggests possible wedge ice.


LANDFORM_TOPOGRAPHY:
Flat to gently sloping interrupted by shallow channels and low scarps. Relief to 10 m, exceptionally to 30 m

LANDFORM_DRAINAGE_PATTERN:
Drainage mainly subsurface with seepage along channels

GROUND_ICE:
As GP, but with locally high segregated ice within silt and below peat in channels.

COMMENTS:
Same as Gp, Gt (above) except in channels which may contain peat and ice-rich silt. Where unit grades into units GLp, GLpk, the surface deposit is typically sand rather than gravel and may be underlain by ice-rich silt.


SURFICIAL_DEPOSIT_MATERIAL:
Glacial till typically clay, silt, minor sand and gravel. Locally up to 90% > 2 mm

LANDFORM_TOPOGRAPHY:
Flat to gently sloping (0-3%) except as indicated by the slope superscript Relief to 5 m

GROUND_ICE:
Commonly 10 to 25% segregated ice as thin (1 mm-2 cm) irregular discontinuous seams in upper 2-3 m. Thicker 10 cm to 3 m+ ice lenses at depth occasionally in Zones 0, 1, 2, rare in Zone 3.

COMMENTS:
Potential subsidences on removal of vegetation typically less than 1 m (but note that unit may have up to 10% unmapped fO or pO, and that locally ice content at depth may be high); because of drainage by numerous sub-parallel runnels, roads or berms normal to slope direction require numerous culverts to avoid impoundment of surface water.


LANDFORM_TOPOGRAPHY:
Moraine plain with individual drumlins, to fluted moraine plain. Slope 2-10 degree Relief to 20 m

LANDFORM_DRAINAGE_PATTERN:
Parallel seepage or streams in fluted moraine, to trellis pattern or deranged drainage in moraine plain with drumlins

COMMENTS:
Similar to tMp; crests of drumlins and drumlinoid ridges typically well-drained, interveining depressions poorly drained; construction of roads, etc. easier parallel to than normal to orientation of drumlins.


LANDFORM_TOPOGRAPHY:
Broad hummocks 10 to 30 m high, 100 to 500 m across Slopes to 10 degree

LANDFORM_DRAINAGE_PATTERN:
Deranged; centripetal to local depressions

GROUND_ICE:
Commonly up to 10%, locally up to 40% segregated ice as thin (1 mm to 2 cm) irregular discontinuous seams in upper 2-3 m. Thicker (10 cm to 3 m+) ice lenses at depth common in Zones 0, 1, occasional in Zone 2.

COMMENTS:
Summits of broad hummocks typically well drained, similar to tMp; lower slopes and intervening depressions may have high ice content, with potential for subsidence of several meters on removal of vegetation; retrogressive-thaw flow slides occur on colluvial slopes (Cx) developed on this unit west of Peel River.


LANDFORM_TOPOGRAPHY:
Individual to coalescent hummocks 15 to 50+m high; Slopes to 20 degree exceptionally 30 degree

LANDFORM_DRAINAGE_PATTERN:
Deranged, centripetal to local depressions

GROUND_ICE:
Highly variable depending upon topographic position; crests of prominent ridges and hummocks well drained and ice-free to depths of 2-5 m; lower slopes as for tMm.

COMMENTS:
Crests of prominent ridges and hummocks offer restricted good construction sites. Ice content and potential for subsidence may be high in depressions.


LANDFORM_TOPOGRAPHY:
Individual and compound straight to sinuous ridges 15 to 50+ m high; Slopes to 20 degree exceptionally 30 degree


SURFICIAL_DEPOSIT_MATERIAL:
Glacial till minor glaciofluvial sand and gravel, glaciolacustrine silt and clay, peat

LANDFORM_TOPOGRAPHY:
Rolling bedrock controlled topography with relief to 150 m Slopes to 15 degree

LANDFORM_DRAINAGE_PATTERN:
Downslope seepage in sub-parallel runnels; permanent streams in valleys

GROUND_ICE:
As tMp, tMv on hilltops and gentle slopes with locally very abundant (up to 40% by vol.) segregated ice in silt and clay filled depressions.


SURFICIAL_DEPOSIT_MATERIAL:
Mainly glacial till; widely distributed glaciolacustrine silt and clay in valleys

LANDFORM_TOPOGRAPHY:
Broadly rolling piedmont slopes on east flank of Richardson Mtns.

LANDFORM_DRAINAGE_PATTERN:
Dendritic (to east) with major streams deeply incised

GROUND_ICE:
As tMp in uppermost 1-3 m; massive segregated ice common in both till and glaciolacustrine sediments at greater depth.

COMMENTS:
Active-layer detachment slides and subsequent retrogressive-thaw flow slides common on colluvial slopes (Cx) developed on this unit.


SURFICIAL_DEPOSIT_MATERIAL:
Cretaceous sandstones, shales. Paleozoic sandstones shales, quartzites, carbonates

LANDFORM_TOPOGRAPHY:
Mainly prominent ridges, scarps and hills developed on resistant sandstones, quartzites and carbonates

LANDFORM_DRAINAGE_PATTERN:
Generally freely drained but with some poorly drained depressions

GROUND_ICE:
No records of segregated ice, but possibility of ice in joints and in fracture zones; segregated ice may be present in silt-filled depressions. Ice-filled fractures observed locally in sandstone in Zone 1, probable also in Zones 0, 2, 3; thin ice lenses possible in shales near surface in Zones 0 to 3.

COMMENTS:
Carbonate rocks of Paleozoic age provide suitable material for rip-rap and crushed aggregate; sandstones and shales of Imperial formation readily rippable to provide fill; shales, especially bentonitic shales, of Cretaceous age subject to massive slides.


# 054_Hughes_OF167_Legends_Sheet2_unglaciated_uplands

NAME:
Mountains developed on sanstone, siltstone, minor shale

LANDFORM_TOPOGRAPHY:
Forms ranging from flat-topped dissected mountains plateau, typically with sandstone capping, to irregular mountainous ridges typically developed on moderately to steeply dipping sandstone, with intervening valleys developed on shale

SURFICIAL_MATERIAL_THICKNESS:
Sandstone, siltstone, rubble; colluvium with silty to clayey matrix 0-3 m

GROUND_ICE:
Little or none on moderate steep slopes; locally high in slope wash sediments on gentle slopes and valley floors

SOILS_TEXTURE_USDA:
Cobbly and gravelly sands and silts, minor silts and clays

SOILS__MICRO_RELIEF:
Sorted nets and stripes, some solifluction terraces, minor hummocks 0-50

ENGINEERING_COMMENTS:
Steep slopes and high relief make much of this unit difficult for location of roads, pipeline, etc. Flattish mountain summits are common in the unit, and afford suitable terrain for most types of construction, but summit areas are mostly separated by intervening steep slopes.


LANDFORM_TOPOGRAPHY:
Forms ranging from flat-topped dissected mountains plateau, typically with sandstone capping, to lrregular mountainous ridges typically developed on moderately to steeply dipping sandstone, with intervening valleys developed on shale


NAME:
Mountains developed on carbonate rocks (limestone dolomite)

LANDFORM_TOPOGRAPHY:
Includes rugged serrate mountains developed on limestone and dolomite white Mountains of paleozoic age (northeastern bell River map area only)

SURFICIAL_MATERIAL_THICKNESS:
Gravelly to blocky colluvium with minor fines 0-3 m+

GROUND_ICE:
Little or none except very locally in slope wash sediments in restricted floors of narrow valleys

ENGINEERING_COMMENTS:
Steep slopes and high relief make this unit highly unsuitable for location of roads, pipelines, etc.; rockfalls and slides common.


NAME:
Mountains and high hills developed on limestone, argillite and chert of Road River Formation

LANDFORM_TOPOGRAPHY:
Steep-sided, sharply rounded, branching mountain ridges developed on Road River Formation on eastern and western flank of southern Richardson Mountains

SURFICIAL_MATERIAL_THICKNESS:
Platy argillite and blocky limestone and chert rubbles with minor fines 0-3 m+

GROUND_ICE:
Little or none except very locally in slope-wash sediments in restricted floors of narrow valleys

SOILS__MICRO_RELIEF:
Soil stripes, minor nets and terraces 0-40

ENGINEERING_COMMENTS:
Gravelly character and low ice content make surficial materials relatively stable; subject to slow solifluction creep on steeper slopes; surficial material is suitable for road or berm construction; near surface bedrock can be ripped; high relief and steep slopes make unit unsuitable for location of roads, pipelines, etc. except on lowest flanks.


NAME:
Mountains and high hills developed on argillites and  quartzites

LANDFORM_TOPOGRAPHY:
Broadly rounded mountains and high hills, developed on argillite and quartzites of Tindir Group (Precambrian)

SURFICIAL_MATERIAL_THICKNESS:
Quartzite and argillite detritus with silty clay matrix; block felsenmeer on upper surfaces developed on quartzite 0-3 m+

SOILS__MICRO_RELIEF:
Sorted nets and stripes, some hummocks 0-40

ENGINEERING_COMMENTS:
Blocky felsenmeer developed on quartzite (mainly forming upper surfaces)is stable but material is too coarse for construction purposes and very difficult to trench. Surficial materials developed on argillite are mainly stable, offering suitable routing for roads and pipelines where relief and slopes are not excessive; locally, the quartzite is deeply weathered to uniform, medium grained white sand. The argillite bedrock is thin bedded and probably readily ripped.


NAME:
Mountains and high hills developed on conglomerates

LANDFORM_TOPOGRAPHY:
Generally well rounded high hills and mountains often modified by cryoplanation, with occasionally a sharp,elongated steeply dipping ridge (c.f. Sharp Mtn.)

SURFICIAL_MATERIAL_THICKNESS:
Gravelly to blocky colluvium with minor fines 0-2 m; locally thicker on lower slopes

ENGINEERING_COMMENTS:
Good drainage and mainly coarse surficial material with low ice content make this a stable terrain; high relief and steep slopes will make most construction difficult.


NAME:
High hills developed mainly on shale with siltstone and sandstone combination

LANDFORM_TOPOGRAPHY:
Intricately dissected, irregular ridges and uplands

SURFICIAL_MATERIAL_THICKNESS:
Clayey colluvium 0.5-2m locally thicker on lower slopes

ENGINEERING_COMMENTS:
Intricate dissection makes this unit very unsuitable for location of roads or pipelines.


NAME:
High hills developed on sandstone and siltstone with minor shale

SURFICIAL_MATERIAL_THICKNESS:
Clayey discontinuous area of silt over weathered sandstone and shale (typically clayey silt to sandy clay with sand-stone fragments; sandstone rubble on scarps and ridges developed on sandstone) 0-3 m+

GROUND_ICE:
Highly variable; generally low to moderate; locally high on lower slopes; nil in prominent ridges developed on sand-stone

SOILS__MICRO_RELIEF:
Sorted stripes, steps, minor hummocks 10-40

ENGINEERING_COMMENTS:
Lower slopes and valley bottoms with potentially thick and ice-rich silt should be avoided; ridges and tops of scarps developed on sandstone or siltstone affords suitable routing for roads, pipelines, etc.; the sandstone and siltstone is mainly thin bedded, readily ripped or crushed, but as road metal is tool soft to with-stand heavy traffic.


SOILS__MICRO_RELIEF:
Sorted stripes, steps, minor hummocks 10-50


NAME:
High hills developed on sandstone and siltstone

SURFICIAL_MATERIAL_THICKNESS:
Rubble of sandstone and siltstone and colluvium composed of rubble in silty matrix 0-3 m+

SOILS__MICRO_RELIEF:
Sorted stripes and nets, minor hummocks 0-40

ENGINEERING_COMMENTS:
Surficial materials mainly highly stable; offers good routing for roads, pipelines except for limitations imposed by slope and relief. The sandstone and siltstone is mainly thin-bedded, readily ripped or crushed but as road metal is too soft to with stand heavy traffic.


SOILS_TEXTURE_USDA:
For tops of hills above tree line see zone O, For lower slopes see S, SiL unit.

SOILS_UNIFIED_CLASSIFICATION:
For tops of hills above tree line see zone O, For lower slopes see S, SiL unit.

SOILS__MICRO_RELIEF:
For tops of hills above tree line see zone O, For lower slopes see S, SiL unit.


LANDFORM_TOPOGRAPHY:
Broadly rounded branching ridges developed on limestone and dolomite of Ordovician -silurian age (old Crow map area); cuesta ridges developed on limestone of Permian and Carboniferous age (southern Eagle River Map area)

SURFICIAL_MATERIAL_THICKNESS:
Gravelly to blocky colluvium with minor fines on slopes; increased fines on flat tops and lower slopes 0-3 m+

ENGINEERING_COMMENTS:
Except for local ice-rich silt on lower slopes and valley floors, surface is highly stable; limestone bedrock is generally thick bedded and probably difficult to rip except in weathered near-surface layer; affords good source of rip-rap or crushed aggregate; high relief and locally steep slopes make unit mostly unsuitable for routing of pipelines, roads, etc.


LANDFORM_TOPOGRAPHY:
Irregular ridges comprised of prominent subsidiary ridges developed on chert with intervening depressions developed on shale

SURFICIAL_MATERIAL_THICKNESS:
Chert rubble (on ridges) to silty clay with chert  fragments (on shale)

GROUND_ICE:
No data; probably little or none in ridges; locally high in upper 2 m in depressions and saddles

ENGINEERING_COMMENTS:
Chert rubble and subjacent bedrock affords good material for road or berm construction (but chert fragments are hard, sharply angular and highly abrasive to machinery and tires).


LANDFORM_TOPOGRAPHY:
Broadly rounded hills and ridges with smooth slopes, summits, commonly surmounted by Tors, developed on granite of Old Crow range and Schaeffer mtn. (Old Crow map area only)

SURFICIAL_MATERIAL_THICKNESS:
Sandy to gravelly detritus derived from granite 0-3 m+

SOILS__MICRO_RELIEF:
Soil stripes, some nets and hummocks 0-30

ENGINEERING_COMMENTS:
The moderate topography, the generally granular character of surficial materials, and low ground ice content of this unit make it highly stable; locally abundant residual granite boulders will pose problems for trenching equipment. Outcropping granite forms tors on hilltops and ridges, where surficial cover is probably thin (1 to 2m); cover is probably thicker on lower slopes. Joint spacing is granite as seen in outcrops along Old Crow River ranges from 1 to 6m in shear zones to 10  feet elsewhere.


NAME:
Low hills, developed on sandstone, minor shale

LANDFORM_TOPOGRAPHY:
Irregular ridges and hills, mostly developed on moderately deformed sandstone and shale

SURFICIAL_MATERIAL_THICKNESS:
Variable cover of silt over weathered sandstone and shale (typically clayey silt to sandy clay with sandstone fragments) 0-3 m; thicker on lower slopes

GROUND_ICE:
Low to high; locally very high in thick silt on lower slopes

ENGINEERING_COMMENTS:
Lower slopes and valley bottoms with potentially thick, ice-rich silt should be avoided; ridges and tops of scarps developed on sandstone or siltstone affords good  routing for roads, pipelines, etc.; the sandstone and siltstone is mainly thin-bedded, readily ripped or crushed, but as road metal is tool soft to withstand heavy traffic.


LANDFORM_TOPOGRAPHY:
Broadly rounded low hills developed on shale and siltstone

GROUND_ICE:
High to very high (locally to 80% ice volume)

ENGINEERING_COMMENTS:
Highly susceptible terrain damage due to degradation of permafrost when vegetation and/or organic cover is removed ; shale may fail by rotational slumping in banks of larger streams.


NAME:
Low hills, dominantly sandstone, siltstone

LANDFORM_TOPOGRAPHY:
Irregular ridges and hills developed on moderately deformed sandstone and siltstone

SURFICIAL_MATERIAL_THICKNESS:
Sandstone and siltstone rubble; veneer of sandy silts on lower slopes, 0-3m possibly thicker in valley bottoms

GROUND_ICE:
Low; locally high in silts on lower slopes and valley floors

ENGINEERING_COMMENTS:
Similar to High Hills developed on same lithologies except for significant areas of silts with high ice content on lower slopes and valley floors; ridges and hills afford good routing for pipelines and roads; lower slopes and valley floors should be avoided.


NAME:
Dissected low hills developed on sandstone and shale, and shale and sandstone

LANDFORM_TOPOGRAPHY:
Dissected plain with rectangular to dendritic drainage developed on flat-lying sandstone and shale of Eagle Plains Formation (west of Eagle River)

SURFICIAL_MATERIAL_THICKNESS:
Discontinuous silt, weathered sandstone and shale; coarse sandstone rubble on scarps developed on sandstone; local peat accumulations on valley floors, 0.5-3 m thicker in valley bottoms

GROUND_ICE:
Low to moderate on flattish upper surfaces and slopes; high to very high (up to 80% ice by volume) on valley floors


SURFICIAL_MATERIAL_THICKNESS:
Discontinuous silt, over gravel (weathered conglomerates) silt 0-3 m

GROUND_ICE:
Nil to moderate; locally high on lower slopes and valley floors

ENGINEERING_COMMENTS:
Locally thick silt with high ice content, unstable when thawed, may be expected on lower slopes and valley floors. On higher slopes, thin silt (1M+-) with high ice content may be encountered, but aggregate ice thickness will be low. Underlying conglomerate is weathered to gravel to unknown depth,


LANDFORM_TOPOGRAPHY:
Broadly rounded hills and ridges with smooth slopes

SURFICIAL_MATERIAL_THICKNESS:
Organic sandy silt with rock (limestone, dolomite) detritus; silt veneer on lower slopes 0-3 m

GROUND_ICE:
Low except in silts on lower slopes, where ice may be locally very high

ENGINEERING_COMMENTS:
Same as High Hills developed on carbonates, but  with lower relief, gentler slopes; silt with high ice content probably more prevalent on lower slopes and valley bottoms than in High Hills developed on carbonates; in general, however, the unit is stable and suitable for routing of roads, pipelines, etc.


NAME:
Low hills developed on argillite and quartzite

LANDFORM_TOPOGRAPHY:
Smooth ridges and hills drainage mainly by downslope seepage

SURFICIAL_MATERIAL_THICKNESS:
Quartzite and argillite detritus with silty clay matrix; quartzite and argillite rubble in restricted summit areas locally thick silt on lower slopes and valley floors  0-3 m

GROUND_ICE:
Low to moderate, high in silts on lower slopes

ENGINEERING_COMMENTS:
Surficial materials stable except for ice- rich silts on lower slopes; mostly suitable for routing of roads, pipelines, etc.


LANDFORM_TOPOGRAPHY:
Broadly rounded undulating plain developed mainly on shale

GROUND_ICE:
High to very high (locally up to 80% by volume)

ENGINEERING_COMMENTS:
Highly susceptible to terrain damage due to degradation of permafrost when vegetation and/or organic cover is removed;should be avoided in routing of roads, pipelines, etc.


NAME:
Pediment developed on sandstone, siltstone and shale in any combination

LANDFORM_TOPOGRAPHY:
Smooth, gentle slope, typically 1 to 3 degree (exceptionally to 8 degree in narrow pediments in mountain valleys) steepening somewhat near upper margin; drainage by downslope seepage; in part with poorly integrated sub-parallel drainage

SURFICIAL_MATERIAL_THICKNESS:
Organic silt commonly overlying poorly sorted gravel silt 1-2 m gravel 1-3 m

GROUND_ICE:
High to very high in silt; mostly low in subjacent materials

ENGINEERING_COMMENTS:
In general, the silty cover is thinnest at upper margin of pediment slope, thicker at lower margin; although ice-content of silt is high, aggregate ice thickness is relatively low because of thinness of silt; burial of pipelines may be possible where trench depth exceeds thickness of silt. Roads or berms routed normal to or diagonally across the direction of slope will require numerous culverts to accommodate the downslope seepage of surface water.


LANDFORM_TOPOGRAPHY:
Smooth, gentle slopes, mostly less than 3 degree

SURFICIAL_MATERIAL_THICKNESS:
Silt, organic silt overlying fine gravel derived from granite silt 0-2 m

ENGINEERING_COMMENTS:
See comments for pediments developed on S, Si, Sh.


LANDFORM_TOPOGRAPHY:
Smooth, gentle slopes, typically less than 5 degree, steepening to 6 degree to 8 degree with gradual transition to hill slopes above

SURFICIAL_MATERIAL_THICKNESS:
Organic silt, silty clay, commonly overlying coarse limestone detritus silt 1-2 m, gravel 1-3 m

GROUND_ICE:
Low to moderate; locally high on lower slopes

ENGINEERING_COMMENTS:
Similar to pediments developed on S, Si, Sh except for subjacent bedrock.


NAME:
Pediment developed on argillite, quartzite and volcanic rocks

LANDFORM_TOPOGRAPHY:
Smooth, gentle slopes drainage mostly by downslope seepage

SURFICIAL_MATERIAL_THICKNESS:
Organic silt, clayey silt over poorly sorted quartzitic gravels silt 0-3 m gravel 1-2 m

GROUND_ICE:
Moderate to very high, with general increase downslope

ENGINEERING_COMMENTS:
Similar to pediments developed on S, Si, Sh except for subjacent bedrocks.


SURFICIAL_MATERIAL_THICKNESS:
Organic silt, overlying gravel (weathered conglomerates)  0.5 to 3 m


# 054_Hughes_OF167_Morphology

DESCRIPTION:
kettled (glaciofluvial) or thermokarst (glaciolacustrine or alluvial)


# 054_Hughes_OF167_Vegetation

DESCRIPTION:
Ericaceae (Ledwm sp., Chamaedaphne, Kalmia etc.)


# surficial_lines

ORIGNL_MAP:
Hughes et al., 1973, Old Crow, GSC Open File 167


ORIGNL_MAP:
Hughes et al., 1973, Bell River, GSC Open File 167


TYPE:
meltwater channel, minor, flow direction unknown


TYPE:
meltwater channel, minor, flow direction known


# surficial_points

ORIGNL_MAP:
Hughes et al., 1973, Old Crow, GSC Open File 167


ORIGNL_MAP:
Hughes et al., 1973, Bell River, GSC Open File 167


# surficial_polygons

ORIGNL_MAP:
Hughes et al., 1973, Old Crow, GSC Open File 167


ORIGNL_MAP:
Hughes et al., 1973, Bell River, GSC Open File 167


