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Student Guide | Cape Cod | Everglades | Los Angeles | Download PDF

Los Angeles:

Introduction

Reading

Focus Question

The Interested Parties

The Los Angeles Area - What You Need to Know

Climate - Warm, Dry Summers and Cool, Wet Winters

The Geologic Hazards of La Crescenta

Debris Basins - Catch It If We Can

NEWSFLASH!

For Your Information: We Have a Plan

Glossary

Glossary:

Use these definitions of important terms as you answer the Focus Question.

clinometer An instrument used to measure angles.
debris flow A moving mass of water-saturated near-surface materials.
earthflow A flowing mass of fine-grained soil particles mixed with water.
sediment Solid rock or mineral fragments transported and deposited by wind, water, gravity, or ice. Sediment accumulates loosely in layers.
erosion The removal of weathered rocks by the action of water, wind, ice, or gravity.
Geologic environment likely to produce earthquake-induced landslides in the Los Angeles region.
Landslide Type Type of Material Minimum Slope Inclination Remarks
Rock falls Rocks weakly cemented, intensely fractured or weakened 40 Common near ridge crests and on spurs, ledges, artificially cut slopes, and slopes undercut by active erosion
Rock avalanches Rocks intensely fractured and exhibiting significant weathering, planes of weakness dipping out of slope, weak cementation, or evidence of previous landsliding 25 Restricted to slopes of > 153 yards relief that are undercut by active erosion
Rock slumps Intensely fractured rocks, preexisting rock slump deposits, shale and other rocks containing layers of weakly cemented or intensely weathered material 15
Disrupted soil slides Loose, unsaturated sands 15
Soil slumps Loose, partly to completely saturated sand or silt; poorly compacted manmade fill composed of sand, silt, or clay; preexisting soil slump deposits 10 Common on embankments built on soft, saturated foundation materials, in hillside cut-and-fill areas, and on river and coastal flood plains
Soil block slides Loose, partly to completely saturated sand or silt; poorly compacted manmade fill composed of sand or silt 5 Common in areas of preexisting landslides along river and coastal flood plains, and on embankments built on soft, saturated foundation materials
Soil earth flows Stiff, partly to completely saturated clay and preexisting earth-flow deposits 10
Soil lateral spreads Loose, partly or completely saturated silt or sand; slightly compacted manmade fill composed of sand 0.3 Common on river and coastal flood plains, embankments built on soft, saturated foundation materials, delta margins, sand dunes, sand spits, alluvial fans, lake shores, and beaches
Rapid soil flows Saturated, slightly compacted manmade fill composed of sand or sandy silt; loose, saturated granular soil 2.3
Subaqueous landslides Loose, saturated granular soils 0.5 Common on delta margins (subaqueous part)
Topographic map of the La Crescenta area. Topographic map of the La Crescenta area.
Click above thumbnails to view the full image. Topograhic map (Activity 3). Study this topographic map of the La Crescenta area. Find the schools mentioned in the focus question, the debris basin, and the foothills of the San Gabriel Mountains. Note every feature, natural of manmade, that would affect children's safety in the event on the occurence of a geologic or hydrologic hazard.

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Student Guide | Cape Cod | Everglades | Los Angeles | Download PDF

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