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2017 El Capitan Horse Tail Falls rock fall

A close perspective of a very large, thick dust cloud billow from the southeast face of El Capitan.

A very large rock fall occurred from the southeast face of El Capitan, near the path of seasonal Horsetail Falls and from the same general areas as the seven rock falls that occurred the previous day. The failed rock mass detached as an intact block and fell to the base of the cliff, fragmenting on impact. The resulting boulders tumbled vertically, over another cliff below the impact ledge and then down the long talus slope below, with boulders coming to rest near and slightly beyond the base of the talus slope. Fragmentation on the impact ledge produced a very large dust cloud. This dust cloud initially traveled down the talus slope and out across the floor of Yosemite Valley, enveloping Northside Drive and limiting visibility to a few tens of meters; it then billowed upward and eastward into eastern Yosemite Valley. The initial impact on the ledge at the base of the cliff produced many smaller "flyrock" fragments, one of which, was launched in a steeply upward from the impact point and traveled approximately 400 m in a ballistic trajectory to Northside Drive, where - improbably - it struck the roof of a moving sport-utility vehicle (SUV), puncturing the sun roof and striking the driver of the vehicle in a glancing blow to his head. As a result, the vehicle veered off the road onto a boulder and was quickly engulfed in dust.

UTM East: 268513; UTM North: 4179220; Elevation: 1752

U.S. National Park Service

Restrictions apply on use and/or reproduction (Copyrighted material): This Item is protected by copyright and/or related rights. Copyright: Olsboe Foreyen, Hennette

Hennette Olsboe Foreyen

Public domain:Restrictions may apply on use and/or reproduction

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Yosemite National Park, Code: YOSE

El Capitan
Latitude: 37.7310163906877, Longitude: -119.62680684

Horse Tail Falls
Yosemite National Park, California
Latitude: 37.8399200439453, Longitude: -119.540397644043

Rock Fall Database GroupID for YOSE : 2017092801
Rock Fall Database ID for YOSE : 2017092801-10

Yosemite Rock Falls Collection

20170928

09/28/2017

Public Can View

Organization: Yosemite NP
Position: Park Geologist
Address: El Portal, CA 95318
Email: greg_stock@nps.gov

Wednesday, May 11, 2022 11:46:07 PM

Thursday, July 28, 2022 9:08:03 PM

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