“Bite-Size Bits of Local, National, and Global History”
“Bite-Size Bits of Local, National, and Global History”
Iverness in Marin County, California — The American West (Pacific Coastal)

Point Reyes Conglomerate

Point Reyes National Seashore

Point Reyes Conglomerate Marker image. Click for full size.
By Don Morfe, July 5, 2009
1. Point Reyes Conglomerate Marker
Photo captions:
Upper photo:
This unique rock formation is exposed on the Point Reyes peninsula.
Center photo:
Most of the colorful stones or “clasts” embedded in the conglomerate are about the size of grapes, but some measure several feet in diameter.
Lower photo:
The sands, pebbles, and boulders that make up the conglomerate were transported by fast-flowing streams, currents, and underwater landslides to the marine environment where the rock formed.
Inscription. The intriguing rock exposure in front of you is part of a formation that caps the highest hills in this area. The Point Reyes Conglomerate is a formation consisting of a sandy matrix embedded with pebbles, cobblestones, and boulders. Geologists estimate that the formation may be over 50 million years old.

Here you can see layers intersecting at different angles (cross bedding), and rounded cavities caused by the erosion of poorly cemented materials. Notice also that in any one layer the larger sand grains which sank first are at the bottom, while the finer ones lie on top (graded bedding)

Please do not chip or pick at the conglomerate.
Leave it intact for others to enjoy.
Erected by National Park Service.
Location. 37° 59.778′ N, 123° 1.2′ W. Marker is in Iverness, California, in Marin County. Marker is on Sir Francis Drake Blvd. Touch for map. The marker is located near the Point Reyes Lighthouse Visitor Center at the Point Reyes National Seashore. Marker is in this post office area: Inverness CA 94937, United States of America.
Other nearby markers. At least 8 other markers are within 3 miles of this marker, measured as the crow flies. Point Reyes Light Station (here, next to this marker); Common Murres
Point Reyes Conglomerate image. Click for full size.
By Don Morfe, July 5, 2009
2. Point Reyes Conglomerate
(within shouting distance of this marker); Point Reyes Light (about 300 feet away, measured in a direct line); The Rock Plants (about 600 feet away); Victims of the Coast (approx. 2.2 miles away); Lives of Sacrifice and Service are Honored Here (approx. 2.2 miles away); Sea Life in These Waters (approx. 2.3 miles away); Whalewatching (approx. 2.3 miles away).
Categories. Environment
Point Reyes Conglomerate Rock Formation image. Click for full size.
By Don Morfe, July 5, 2009
3. Point Reyes Conglomerate Rock Formation
Credits. This page was last revised on June 16, 2016. This page originally submitted on February 16, 2013, by Don Morfe of Baltimore, Maryland. This page has been viewed 304 times since then. Photos:   1, 2, 3. submitted on February 16, 2013, by Don Morfe of Baltimore, Maryland. • Syd Whittle was the editor who published this page.
Editor’s want-list for this marker. Wide area view of the marker and its surroundings. • Can you help?
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