The Ground Beneath Your Feet

The Ground Beneath Your Feet (HMZ66)

Location: Daly City, CA 94015 San Mateo County
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Country: United States of America
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N 37° 41.862', W 122° 29.79'

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Here at Thornton Beach, the ground is not as solid as it seems. The ground itself is made up of a semi-consolidate sedimentary rock from here to Mussel Rock. It doesn't hold together well, which makes the coastline very unstable.

Constant pounding of the surf along Daly City coast undercuts the cliffs. Rain scours and penetrates the soil loosening the rock structure. Gravity pulls the weakened slopes down in slumps and slides. If that weren't enough, the San Andreas Fault runs 1/4 mile from this spot. Ground shaking from earthquakes causes landslides too. Geologists believe the shelf below you, between this elevation and the shore, is a mighty rotational slump triggered by the 1906 earthquake.

This Daly City beach was once accessible by road. In 1982 heavy rains and unusually large tidal action undercut the cliffs from Thornton Beach south to Mussel Rock, causing a massive landslide. Concern over safety keeps the 56-acre property and beach inaccessible.
HM NumberHMZ66
Marker ConditionNo reports yet
Date Added Thursday, October 9th, 2014 at 10:53am PDT -07:00
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Locationbig map
UTM (WGS84 Datum)10S E 544386 N 4172394
Decimal Degrees37.69770000, -122.49650000
Degrees and Decimal MinutesN 37° 41.862', W 122° 29.79'
Degrees, Minutes and Seconds37° 41' 51.72" N, 122° 29' 47.40" W
Driving DirectionsGoogle Maps
Area Code(s)650, 415
Closest Postal AddressAt or near 5775 Thornton Beach Rd, Daly City CA 94015, US
Alternative Maps Google Maps, MapQuest, Bing Maps, Yahoo Maps, MSR Maps, OpenCycleMap, MyTopo Maps, OpenStreetMap

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