Discovering coastal fossils, minerals and strange stumps
By Jason Evans Of the News-Times

A rooted stump at Moolack Beach is a remnant of an ancient forest, and is among many such stumps that are periodically exposed on Oregon's beaches. (Photo by Jason Evans)

Exploring Moolack beach with Oregon's fossil guru, Guy DiTorrice, is an adventure in geologic history. DiTorrice reads the array of rocks and sand on the beach, scans the seawall for scarps, and knows just where to look for treasure.

DiTorrice said, "Oregon coast fossils are found in three formations. The Astoria Formation is approximately 15 million years old, and features sandstone layers mixed with compressed volcanic ash; also Nye mudstone, which is slightly older; and on south Oregon beaches, the Coledo Formation, identified by specimens of dark ash and sand, which are 25 to 30 million years old. These formations of compacted sand, volcanic ash, and river-borne silt are uplifted from the Pacific Ocean floor by geo-plate movement. The combination of eroding basalt, mud, and sandstone produce deposits of rock, fossil and sand found on Oregon beaches."

There are dozens of species of fossilized marine and terrestrial life to be discovered at Moolack Beach. DiTorrice even identified "fossilized poop," amid the bric-a-brac.

In the 1960s Guy Pearson researched the fossil record of the area. Many of the fossils Pearson discovered are displayed at the Smithsonian Museum of Natural History in Washington, D.C.

DiTorrice said during winter storms waves expose and cover the rocks on the beach. To augment summer excursions he tosses less than perfect fossils and other fun finds up to the top of the beach.

Scanning the exposed rocky substrate, DiTorrice looks for clues like wear patterns on rocks, indicative of recent disturbance, and the telltale patterns of the cellular structure of wood grain or bone. He uses his rake to turn over sections of smooth rocks to discover hidden treasures beneath, and to gauge the depth of the rocky deposits.

Concretions are fossils encased in rock, which often erode from the Astoria and Nye formations, and are found on Moolack Beach. One common concretion is typically the size of a flattened hand, rounded, but flat and smooth. With a few careful taps the rock is split to reveal a fossilized scallop.

Other concretions are small, gray, round rocks, which DiTorrice said filter up from the deeper underground. These he calls "Cracker Jack" rocks, because, "you never know what's inside." One such split-rock revealed the fossilized leaf impression of Oregon grape, Mahonia repens.

In some areas, north of Moolack Beach, vertical and horizontal troughs are cut into surf zone sandstone shelves. The vertical troughs are perpendicular to the surf zone and drain materials from the sea wall. The horizontal troughs, parallel to the surf zone, DiTorrice noted, are good hunting grounds, often repositories for fossils and agates.

DiTorrice explained the differentiation between bivalve and gastropod fossils: "Bivalves (for example, clams) have shells divided on a left-right axis and are generally hinged together with a single adductor muscle ... during growth gastropod shells twist 180 degrees, a process called torsion (snails are examples of gastropods)." An example discovered recently was the fossilized remains of the bivalve Katherinella angustri, a common clam, easily recognizable by the apostrophe shaped "hinge."

Among petrified woods, common at Moolack Beach, is Teredo wood, which is named for the signature Teredo clam-bored holes. Other petrified woods include "softwood species of pines and some hardwoods, including alder, myrtlewood, and oak, as well as petrified palm," DiTorrice said.

Fossilized bone is another interesting find, and has characteristic patterning - as though decorated with tiny uniform fractures. Among bones discovered DiTorrice identified the fossilized remains of a fish head and a mammal vertebra.

Another draw for coast visitors is the search for agates, most often found along the wave break at lower tides. DiTorrice explained agate fills voids in sandstone, wood and other organic materials including vacant seashells, solidified under immense pressure over millennia. Agate is a quartz, which has a base chemical composition of crystallized silicone dioxide. Some agates are stained by rust, or other chemical reactions, and so appear colored. An example is iron rich carnelian. The lapidary peoples, DiTorrice said, called many of these stained agates, which are not translucent, jaspers. An arbitrary distinction today is based on a translucence-test of a quarter inch slice of mineral.

Vugs occur when agate crystallizes in geologic voids evidenced at the surface of the host rock. This may be contrasted with geodes, which encase clusters of agate.

Environmentally conscious, DiTorrice is always collecting and carting out recyclable, and other non-natural materials, from the beaches he combs.

DiTorrice cautioned, while Oregon's beaches are public, the seawalls above them, where people's homes and public highways are located, generally are not. "Do not use tools to remove anything from a seawall - this is a violation of Oregon law."

He also stressed beach safety, including sturdy footwear and a wary disposition. Sneaker waves suddenly wash farther ashore than is common for the tide. Waves are forceful enough to knock a person off balance, and drag them out to sea.

Strange stumps

Remnants of ancient forests, scientists and amateurs alike have wondered about hundreds of rooted stumps, periodically exposed on Oregon beaches.

The Holocene Epoch is the current epoch and began 10,000 years ago. The rooted stumps that remain likely belonged to trees living approximately 4,500 years old.

Several such stumps are currently visible at Moolack Beach. In their paper, "Episodically buried forests in the Oregon surf zone," Roger Hart of the College of Oceanic and Atmospheric Sciences with Oregon State University at the Hatfield Marine Science Center in Newport, and Curt Peterson of the Department of Geology at Portland State University, write "The live trees that left the stumps must have grown on the (Holocene) wave-cut platform after regression of the surf zone. Following at least several hundred years of growth, transgression of the surf zone must have invaded the tree growing zone."

Hart and Peterson write, "The forest was inundated by a transgressing surf zone that could have been the result of eustatic rise of sea level and/or removal of sand barriers and/or tectonic subsidence."

The stumps are remarkably well preserved by the cold salt water conditions of the Pacific Ocean. DiTorrice said some exposed stumps are inhabited by barnacles, ship worms and Teredo clams, but most are scrubbed clean by sands when covered and uncovered by winter wave action.

Guy DiTorrice is available for presentations and as a field guide. For more information visit his website at www.oregonfossilguy.com, e-mail guy@orcoast.com, or call 961-1762.

Jason Evans is a reporter for the News-Times. He can be reached at 265-8571 ext. 212, or jevans@newportnewstimes.com.