Part 11Part 11

RECOGNITIONRECOGNITIONFEATURES FEATURES

ofofTRANSLATIONAL TRANSLATIONAL BLOCK SLIDESBLOCK SLIDES

Topographic Expression of Topographic Expression of Translational Block SlidesTranslational Block Slides

• Extended ridges or topographic knobs

• Convergent drainage

• Sharp downslope turns in contour lines

Topographic Patterns on Topographic Patterns on Composite LandslidesComposite Landslides

• Use drainage and topographic keys to recognize anomalous site characteristics typical of landslides– Extended ridges

or isolated knobs– Sudden turns in

hillside contours– Convergent

drainage

Crowley’s Ridge Translational Crowley’s Ridge Translational Block SlidesBlock Slides

Translational landslides are usually fairly large and involve underlying bedrock strata

TRANSLATIONAL BLOCK SLIDESTRANSLATIONAL BLOCK SLIDESTranslational slides tend to detach along pre-existing geologic discontinuities

The geologic structure generally mimics the regional trends, making many of the older slides difficult to recognize

Dormant deep-seated bedrock slides are often characterized by Y-shaped tributaries, anomalous benches, and arcuate headscarp evacuation scars