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Contents

• 1. Summary

• 2. Introduction

• 3. Physical Impacts
  • 3.1 Slide Fill Erosion

  • 3.2. Slide Beaches

  • 3.3. Slide Plumes

  • 3.4. Nearshore Habitats

• 4. Ecological Impacts
  • 4.1. Intertidal Communities

  • 4.2. Subtidal Communities

• 5. References

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List of Figures

• Figure 1. Place names near Lone Tree landslide (right) and close up of the coast from Slide Ranch to the south end of Stinson Beach (left).

• Figure 2. Lone Tree landslide in February, 1971, before the earthquake.

• Figure 3. Lone Tree landslide in September, 1990, almost a year after the earthquake and the beginning of the slide manipulation.

• Figure 4. Lone Tree landslide in October, 1991, after completion of the landslide manipulation showing the initial development of the slump areas on the slide fill and burial of intertidal rock.

• Figure 5. Lone Tree landslide in November, 1992, showing cliff development on the south end of the fill, a large slump forming in the center of the fill, and extensional cracks on the fill plateau.

• Figure 6. Lone Tree landslide in October, 1993, showing a large slump in the central area of the fill.

• Figure 7. Lone Tree landslide in November, 1994, showing additional slumping on the slide face.

• Figure 8. Lone Tree landslide in May, 1995, showing steep cliffs along the fill toe, retreat of the toe from the previously buried intertidal rock, and better development of extensional cracks on the fill plateau.

• Figure 9. Lone Tree landslide in June, 1994, showing vertical cliff development on the slide toe, massive slumping from the central slide, and erosional runnels along the northern face which all contributed to the extensive rock armoring in the intertidal zone.

• Figure 10. Seven topographic profiles along the slide fill showing erosion from 1990 to 1994.

• Figure 11. Geological hazards of the Lone Tree slide in 1994.

• Figure 12. Toe of the Lone Tree landslide in June, 1990, before the slide manipulation. Looking south from the overview on the rocky outcrop between the slide and Lone Tree Creek beach.

• Figure 13. Rocky habitat at the slide toe of Lone Tree landslide in May, 1990, before the slide manipulation.

• Figure 14. (a) View of Lone Tree South Slide beach in July, 1991, immediately after the slide manipulation, and (b) in March, 1993. Photographed from the fill face looking south.

• Figure 15. (a) View of Lone Tree South Slide beach in July, 1991, immediately after the slide manipulation, and (b) in May, 1995. Photographed from the south end of the beach looking north.

• Figure 16. (a) Armoring of the slide toe in June, 1991, and (b) in May, 1995. Photographed from the intertidal rock looking north. Note the increase in the width of the intertidal zone and the retreat of the fill toe.

• Figure 17. Large sediment plumes off Duxbury Reef and Lone Tree landslide in May, 1991.

• Figure 18. (a) Extensive natural sediment plumes along the Lone Tree coastline from Muir Beach, to the south, and beyond the slide to the north. Lone Tree landslide is outlined in red. (b) Highly persistent natural sediment plume around Duxbury Reef in November, 1991.

• Figure 19. (a) Lone Tree slide sediment plume in April, 1993, showing northward transport nearshore and southward transport offshore. (b) Normal sediment plume configuration off the Lone Tree landslide. Photograph taken in April, 1992.

• Figure 20. (a)Sea floor features and (b) bathymetry of Lone Tree slide vicinity in June, 1994

• Figure 21. (a)Sea floor features and (b) bathymetry of Lone Tree slide vicinity in October, 1994.

• Figure 22. Rocky intertidal habitat at Slide Ranch in October, 1990.

• Figure 23. Close-up of the algal community in the mid intertidal zone in October, 1990 at (a) South Slide and (b) Slide Ranch.

• Figure 24. Burial of rocky intertidal communities along the South Slide beach in (a) June, 1991, and (b) July, 1991, directly after the slide manipulation.

• Figure 25. Typical sediment scour of rocky intertidal communities along South Slide beach.

• Figure 26. Some of the rich encrusting marine invertebrate communities on the sides of intertidal rocks in November, 1990, which were buried on South Slide beach by the slide manipulation in 1991.

• Figure 27. Colonization by green algae of intertidal rocks below the slide fill toe, August, 1992.

• Figure 28. Mussel and gooseneck barnacle communities on the tops of the intertidal rocks at the slide toe in June, 1991. These communities periodically colonized isolated rocks below the slide toe and on South Slide beach.

• Figure 29. Intertidal habitats around the Lone Tree slide in 1990, before the slide manipulation.

• Figure 30. Algae composition and cover at Slide Ranch

• Figure 31. Algae composition and cover at Pelican Point

• Figure 32. Algae composition and cover at Slide face

• Figure 33. Algae composition and cover at South Slide.

• Figure 34. Subtidal rock wall communities (a) at the bottom (0-50 cm) and (b) at 1.5 m above the bottom on the North Pinnacle directly in front of the slide in August, 1993.

• Figure 35. Subtidal rock wall communities (a) at the bottom (0-50 cm) and (b) at 1.5 m above the bottom on the North Pinnacle directly in front of the slide in October, 1994.

• Figure 36. Rock wall communities on pinnacle which are scoured by sediment from the McWay landslide in Big Sur, showing colonization of exposed substrate by barnacles.