17—Landslide and Mass-Wasting Features

Federal Geographic Data Committee FGDC Document Number FGDC-STD-013-2006 FGDC Digital Cartographic Standard for Geologic Map Symbolization Appendix A 17—LANDSLIDE AND MASS-WASTING FEATURES REF NO DESCRIPTION SYMBOL CARTOGRAPHIC SPECIFICATIONS* NOTES ON USAGE* linecolor 60% black lineweight .2 mm May be used to outline Outline of slip surface of landslide—Identity and 17.1 area of slip surface of existence certain, location accurate H-8 (60% black) landslide if desired. ? Do not use to outline Outline of slip surface of landslide—Identity or 17.2 ? .75 mm landslide deposits (use existence questionable, location accurate 12.0 mm a map-unit boundary contact instead). Outline of slip surface of landslide—Identity and 17.3 3.5 mm existence certain, location approximate ? Outline of slip surface of landslide—Identity or exis- 17.4 tence questionable, location approximate ? .75 mm .75 mm

Outline of slip surface of landslide—Identity and 17.5 1.5 mm existence certain, location inferred ? Outline of slip surface of landslide—Identity or exis- 17.6 tence questionable, location inferred ? .75 mm .75 mm

Outline of slip surface of landslide—Identity and 17.7 .5 mm existence certain, location concealed ? Outline of slip surface of landslide—Identity or exis- 17.8 tence questionable, location concealed ? .75 mm .75 mm

pattern 431-K Downslope edge of slip 17.9 Area of slip surface of landslide in 50% black outline of surface is usually con- (rotated so lines slip surface parallel slip [lineweight cealed by landslide direction) .2 mm, in deposits or debris mate- 60% black] 17.10 Direction of downslope movement of landslide rials. contact Landslide arrows may [lineweight be shown singly or in Landslide deposits—Arrows show direction of 50° 2.0 .15 mm] pairs. 17.11 mm downslope movement arrow lineweight .175 mm length and curve of arrow may vary Head or main scarp of landslide—Active, sharp, all lineweights .25 mm Place line along crown 17.12 distinct, and accurately located. Hachures point of scarp. down scarp hachure height 1.0 mm; spacing 1.75 mm May be shown in red or Head or main scarp of landslide—Inactive, sub- .5 mm other colors. 17.13 dued, indistinct, and (or) approximately located. Hachures point down scarp 3.0 mm HI-7 Head or main scarp of landslide—Showing height 0.8 0.8 17.14 (in meters). Hachures point down scarp

Head or main scarp of rotated block in landslide— 5.0 mm arrow 17.15 Arrow shows direction of oblique slip. Hachures lineweight .175 mm point down scarp 2.5 mm 15° Internal or minor scarp in landslide—Active, sharp, all lineweights .25 mm 17.16 distinct, and accurately located. Hachures point down scarp hachure height .75 mm; spacing 1.25 mm Internal or minor scarp in landslide—Inactive, sub- .5 mm 17.17 dued, indistinct, and (or) approximately located. Hachures point down scarp 2.0 mm HI-6 Internal or minor scarp in landslide—Showing 0.3 0.3 17.18 height (in meters). Hachures point down scarp

Internal or minor scarp of rotated block in landslide 4.5 arrow mm lineweight 17.19 —Arrow shows direction of oblique slip. Hachures .175 mm point down scarp 15° 2.0 mm *For more information, see general guidelines on pages A-i to A-v.

A–17–1 Federal Geographic Data Committee FGDC Document Number FGDC-STD-013-2006 FGDC Digital Cartographic Standard for Geologic Map Symbolization Appendix A 17—LANDSLIDE AND MASS-WASTING FEATURES (continued) REF NO DESCRIPTION SYMBOL CARTOGRAPHIC SPECIFICATIONS* NOTES ON USAGE* 3.0 mm 60° Place line along base of Main toe of landslide—Active, sharp, distinct, and 17.20 1.0 mm toe; sawteeth on over- accurately located lineweight .25 mm riding block. .5 mm May be shown in red or Main toe of landslide—Inactive, subdued, indistinct, 17.21 other colors. and (or) approximately located 3.0 mm Minor toe, internal thrust fault, or pressure ridge in 2.5 mm 60° 17.22 landslide—Active, sharp, distinct, and accurately .85 mm located lineweight .25 mm Minor toe, internal thrust fault, or pressure ridge in .5 mm 17.23 landslide—Inactive, subdued, indistinct, and (or) approximately located 2.0 mm Minor toe, internal thrust fault, or pressure ridge in lineweight 60° .25 mm 17.24 landslide, showing transport reversal—Active, .85 mm 5.0 sharp, distinct, and accurately located .85 mm mm 60° Minor toe, internal thrust fault, or pressure ridge in .5 mm 17.25 landslide, showing transport reversal—Inactive, subdued, indistinct, and (or) approximately located 2.0 mm Arrow shows sense of Right flank of landslide or right-lateral shear feature 15° 2.5 mm 17.26 arrow lateral movement. —Active, sharp, distinct, and accurately located 5.0 lineweight lineweight .25 mm mm .175 mm Place arrow on side of Right flank of landslide or right-lateral shear feature .5 mm moving ground or on 17.27 —Inactive, subdued, indistinct, and (or) approxi- displaced earth materi- mately located 3.0 mm als. Right flank of landslide or right-lateral shear feature .5 mm In cross section, can also be used to show 17.28 —Concealed by landslide deposits or debris mate- plane of slope failure. rials .5 mm HI-7 May be shown in red or Right flank of landslide or right-lateral shear feature 2.3 2.3 other colors. 17.29 —Showing amount of offset (in meters)

2.5 mm Left flank of landslide or left-lateral shear feature— 15° 17.30 arrow Active, sharp, distinct, and accurately located 5.0 lineweight lineweight .25 mm mm .175 mm Left flank of landslide or left-lateral shear feature— .5 mm 17.31 Inactive, subdued, indistinct, and (or) approximately located 3.0 mm Left flank of landslide or left-lateral shear feature— .5 mm 17.32 Concealed by landslide deposits or debris materials .5 mm HI-7 Left flank of landslide or left-lateral shear feature— 2.3 2.3 17.33 Showing amount of offset (in meters)

hachure height all lineweights .2 mm Hachures point into .5 mm 17.34 Open tension crack or fracture on landslide crack. 1.5 mm all lineweights .2 mm May be shown in red or 17.35 Tension crack or fracture on landslide (1st option) other colors. 1.0 mm all lineweights .2 mm 17.36 Tension crack or fracture on landslide (2nd option) 1.2 mm dash .375 mm; space .325 mm lineweight .2 mm 17.37 Tension crack or fracture on landslide (3rd option)

2.5 mm Arrow shows sense of En echelon cracks or fractures on landslide, indicat- 15° 17.38 crack arrow lateral movement. ing right-lateral shear lineweights 5.0 lineweight .2 mm mm .175 mm May be shown in red or 2.5 mm other colors. En echelon cracks or fractures on landslide, indicat- 15° 17.39 crack arrow ing left-lateral shear lineweights 5.0 lineweight .2 mm mm .175 mm line length can vary 60° May be shown in red or Anticlinal soft-sediment fold, buckle fold, bulge, or 1.0 mm 17.40 2.0 mm other colors. linear ridge on landslide arrow lineweight lineweight .25 mm .175 mm line length can vary 17.41 Dome structure or bulge on landslide 60° 1.0 mm lineweight .25 mm 60° Synclinal soft-sediment fold or linear depression on 1.0 mm 17.42 1.0 mm landslide arrow lineweight line length can vary .175 mm 1.0 mm line lengths can vary 17.43 Basin structure or depression on landslide 60° .75 mm *For more information, see general guidelines on pages A-i to A-v.

A–17–2 Federal Geographic Data Committee FGDC Document Number FGDC-STD-013-2006 FGDC Digital Cartographic Standard for Geologic Map Symbolization Appendix A 17—LANDSLIDE AND MASS-WASTING FEATURES (continued) REF NO DESCRIPTION SYMBOL CARTOGRAPHIC SPECIFICATIONS* NOTES ON USAGE* lineweights .175 mm .65 mm 17.44 Crest line of lateral levee on landslide (1st option) 1.0 60 mm ° 1.5 mm .65 mm 17.45 Crest line of lateral levee on landslide (2nd option) 1.0 60 mm ° 1.5 mm all lineweights .2 mm 1.375 17.46 Path of gully on landslide mm 25° 4.5 mm 1.575 mm lineweight .2 mm 1.0 mm Arrow points downhill. 17.47 Soil creep or incipient sliding on landslide 20° 6.75 mm May be shown in red or 1.5 mm other colors. lineweight .2 mm Tail points downhill. 17.48 Spring, seep, or drainage (runoff) on landslide May be shown in red or circle diameter 1.5 mm; tail length 3.0 mm other colors. all lineweights hachure height Hachures point into Sag pond or closed depression on landslide (map- .875 mm; 17.49 .175 mm depression. ped to scale) spacing 1.25 mm all lineweights hachure height Hachures point away .175 mm .875 mm; 17.50 Hummock on landslide (mapped to scale) spacing from hummock. 1.25 mm all lineweights Hummock on landslide (shown as point symbol .175 mm 60° .875 17.51 when too small to outline at map scale) mm circle diameter 1.5 mm 4.0 mm lineweight Usually shown on 30° 17.52 Tilt direction of surface of landslide 1.125 mm .2 mm special-purpose land- 2.0 mm 2.0 mm slide activity maps. HI-6 May also be shown in Tilt direction of surface of landslide—Showing 14 14 17.53 red or other colors. angle of tilt

lineweight .2 mm 1.75 mm 17.54 Displacement vector—Showing bearing 6.75 25° mm HI-7 Displacement vector—Showing bearing and dis- 1.3 1.3 17.55 tance

1.5 mm Usually shown on Active, reactivated, or historically active debris flow, 17.56 4.0 mm special-purpose land- showing a sharply defined morphology color 100% 20° magenta slide activity maps. Dormant-young debris flow, showing a fresh and If necessary, alpha- 17.57 uneroded morphology but having no evidence of numeric characters may historic activity color 50% magenta be added to help distin- guish landslide areas. Active, reactivated, or historically active landslide fill color 60% May also be shown in 17.58 (mapped to scale), showing a sharply defined magenta morphology red or other colors. Dormant-young landslide (mapped to scale), show- fill color 40% 17.59 ing a fresh and uneroded morphology but having magenta no evidence of historic activity fill color 20% Dormant-mature landslide (mapped to scale), 17.60 magenta showing a smoothed and eroded morphology

Dormant-old or relict landslide (mapped to scale), fill color 8% 17.61 magenta showing a weak morphology

Rock slide, slump, block-glide landslide, rotational .5 mm Usually shown on draft as shown 17.62 landslide, or Toreva block, consisting of a relatively all lineweights special-purpose land- intact mass of displaced materials 90° .3 mm slide activity maps. May also be shown in Earth flow, consisting of a relatively thick and jum- 17.63 draft as shown all lineweights red or other colors. bled mixture of displaced materials .3 mm 90° If necessary, symbols 1.0 mm may be enlarged or Debris slide, consisting of a loose and relatively 17.64 4.5 mm reduced. shallow veneer of displaced materials all lineweights 90° .3 mm Debris-slide slope (mapped to scale), consisting of fill color Usually shown on 17.65 coalesced scars of landslides and debris flows that 20% black special-purpose land- are too small or numerous to be shown at map scale slide activity maps. *For more information, see general guidelines on pages A-i to A-v.

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