Landslide Dynamics of Trinity Ravine

Ted Chwalk

Elton Ham

Purpose

View Dynamics of Ravine and Gullies Determine Depositional Environment Hypothesis how depositional environment

effects soil stability

Methods

Visual Observations– Ravine– Gullies– Landslide

Soil Pits– 4 soil pits – Stratigraphic columns

Ravine

Gullies

Landslide w/ Soil Pits

Pit #4

Key

Data: Gullies

2/3 Gullies had active landslides

All had scarps ~1m high

All scarps had thick organic layer at surface

Data: Soil Pits

Data: Soil Pit Stratigraphic Column

Depositional Environment

Champlain Sea Lake Vermont Post Glacial

Discussion

Infiltration Rates in Sediments – Organic Topsoil

1-4mm/hr

– Sand 4-8mm/hr

– Silt 1-4 mm/hr

– Heavy Clay 0-1mm/hr

Conclusions Heavy Clays + Silt = Saturated Soil Saturated Sand and Topsoil = Slope Failure

– Liquification Landslides are the primary processes effecting

erosion What do Landslides and Gullies Have in

Common?– Landslide Erosion creates gullies– Landslide in Ravine = Possible Gully Formation

Things we would have done differently

Direct Study of Infiltration Rates

Quantitative Study of Local Landslide Dynamics, Gully formation, and how it relates to Sediment Transport

Questions ???