The Mysterious Shapes Found at Oregon Coast's Fogarty Beach
Published 11/21/2015 at 2:55 AM PDT
By Oregon Coast Beach Connection staff
(Depoe Bay, Oregon) – Something really weird and astounding lurks beneath the sands of Fogarty Beach, on the central Oregon coast. This popular beach spot is already well known for its freakishly large grains of sand (which can be a bit ouchy in your bare feet) and rocky curiosities. But what lies below them is downright amazing.
These unusual sights show up very rarely: only when sand levels get scoured out by winter storms to extremely low levels. Jagged grooves show when the bedrock here is uncovered. Wild fossils lurk in the rocks (some of which are even viewable when sand levels are more normal). And then there are these objects almost impossible to describe.
As shown in the photo at top, these are the massive grooves in the bedrock of Fogarty Beach, as seen in early 2007. During that winter – and the following one – sand levels got so low that all kinds of things were uncovered.
These have an interesting explanation, according to local experts like Guy DiTorrice, Laura Joki of Lincoln City agate shop Rock Your World, and geologist Jonathan Allan, Ph.D with the Oregon Department of Geology and Mineral Industries.
Both Allan and Joki agreed the bedrock is of the Astoria formation, which is about 15 to 20 million years old. This part of it is mudstone, and the grooves are what geologists term “rills” which have been eroded into this rock.
“This occurs through a variety of approaches, including wave action (oscillatory currents), abrasion (especially when sand levels that periodically cover the platforms fall below 30 cm, the sand begins to act as an abrasive), cavitation (hydraulic effects), and wetting/drying cycles (exposure to sun),” Allan said. “Biological effects can also contribute to some of this.”
In other words, it's a combo of waves digging at it, the sand grinding into it, and changes in how dry or wet the rock is.
Then there's that truly unique object that looks like an egg. Joki and Allan say it's a “concretion,” something built up very slowly over time. Where to stay in this area - Where to eat - Map and Virtual Tour
“The light thing sticking out of the darker rock is a concretion, a rock formed around old dead things that died and sunk to the bottom of the ancient ocean,” Joki said. “Sometimes there are fossils in the concretions, sometimes not.”
Allan said concretions form through various chemical reactions.
“Essentially they form by the precipitation of mineral cement within the spaces between particles,” Allan said.
These can be found in sedimentary rock or soil.
Then there is that touch of Jurassic Park at Fogarty, with the fossil of a large scallop called a petcin. It too is around 15 to 20 million years old, Allan and Joki said. They are the ancient relatives of the sea scallops we know today. More of these Fogarty Beach oddities below and at the Depoe Bay Virtual Tour, Map.
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