We convened the next morning, bright eyed and bushy tailed, at Sunset Bay to finish the Armentrout and Blackwell tour. We had rearranged the trip schedule somewhat the day before, so two stops situated between Simpson Reef and Simpson Cove had not been visited. These sites, Ocean View Lookout and Collapse Cave Point, featured Lower Coaledo stratigraphy. We arrived in the morning mist from a short walk to the edge of the cliff.

The stratigraphy here is largely sandstone which is resistant to erosion despite the waves that pound the shoreline. We descended to the sandstone shelf just below the 80,000 year old Whiskey Run terrace that caps the Coaledo stratigraphy. Dave Blackwell pointed out a disconformity contact from channel scour. Just above the contact he showed us the remnants of a log that had been nearly consumed by ship worms (Teredo worms). Nearby this was a jutting sandstone layer which contained ripple marks showing the direction of the paleocurrent which has been bored in several places by the paleomagnetics team, which includes David and his son Noel. Scott Bogue from Occidental College has also done some of this work. In this area the organics-rich mud layers have been scoured out to deeper water where they might be forming petroleum. John and Dave point out some mud rip up clasts embedded in the sand which confirm this.

The group then made its way a bit further north along the cliff top to the Collapse Cave Point. Armentrout told the group that all the parasequences of the Coaledo formation had been carefully correlated and mapped on the Cape Arago shoreline, even across the cove faults. This stop featured parasequences #5 and #6 in the Lower Coaledo. Armentrout and Blackwell pointed out sandstone dikes through thin mudstone layers between the layers of sandstone. Sandstone is both porous and permeable, but the mudstone layers are not. Therefore, when the layers settle after deposition, the sand layers compact to more stable configurations and the excess water between the grains become pressurized. The dikes push through the mud to relieve that pressure. From an oil geologist standpoint, if one is looking to find oil in that sandstone, the presence of the dikes would be a bad sign that the oil has probably escaped.

After visiting these sites, the group headed around Coos Head, through Charleston, and up the east bank of the Coos Bay shipping channel to the area near Fossil Point. We parked near the little pumphouse just to the south of the Dairy Queen on the Cape Arago Highway. John and many of the locals call this “Stinky Cove” because of the rotting organic smells issuing from it, but in the literature, he refers to it as Beacon Lane Cove. Here we were located on the east side of the South Slough syncline, a trough in the folding pattern of the stratigraphy. It was about low tide or shortly after low tide, so the group hurried across the seaweed-strewn point and south over the Empire Formation terrace to get a half mile or so down the shore to the main show. Along the way Armentrout pointed out pectin shells, trace fossils, and other interesting features of this fossiliferous layer.

As the group approached a barrier point, John pointed out two fossils sticking out of the Empire terrace that appear to be a whale skull and rib. There have been several whale fossils recovered from the Empire formation here. Then the group assembled at the barrier, where we saw an unconformity between the bulk of the Empire Formation overlain by a spectacularly fossiliferous Coos Conglomerate which forms the “point” of Fossil Point. A short climb over the high point put us onto Fossil Point proper, an incredible mass of 8 million-year-old cemented shells. Armentrout pointed out a number of fossils here, including the slipper shell Crepidula, which can be found in stacked groups in this deposit, which must have formed in a niche of calm shallow water. And with that Armentrout’s presentation was completed and he headed off down the shoreline. The rest of the group convened in the picnic grounds at Sunset Bay and had a very relaxing picnic.

Return to the beginning of the article.

Go on to Day 4.

Pictures from Day 3:

We assemble in the fog at the Ocean View Lookout on Day 3.

John demos his legendary status as “Pope John” of Mobil Oil.

Dave points out an ancient log consumed by Teredo worms above the contact.

John takes a rare breather atop the Lower Coaledo stratigraphy.

John explaining some of the clues to the direction of flow which emplaced these sediments.

This shot shows the draping marks in the layer which demos flow to the left.

John points out where the sandstone layer steps down the slope over which it flowed.

Ripple marks are other clues to the direction of flow, and this layer demos that. Holes were drilled for paleomag samples.

The group pushes their way through the overgrown path to the Collapse Cave Point.

Dave points to sand dikes in the thin mud layers at Collapse Cave Point. Stratigraphy is Lower Coaledo.

This shot contains both a carbonized piece of wood and a petrified piece of wood. Two different preservation processes within the same area.

Another shot of the stratigraphy with paleomag holes drilled into the concretions.

One of the sand layers is discontinuous as the stratigraphy heads northward. The continuous layers grade into mudstone to the north.

This picture of Shelly shows off the honeycomb weathering that is very characteristic of rock exposed to salt spray.

The group contemplates the stratigraphy and scenery as the fog disperses.

A classic shot of Shore Acres was taken by Laurie before we departed.

Shore Acres in a less benign mood in 2011.

Good thing we weren’t crawling over the cliffs in weather like this.

Our feet make it to the Empire Formation near Fossil Point.

This stratigraphy in the Coos Bay shipping channel is only accessed at low tide.

John joked that a competing oil company left their trademark up and down the Empire Formation.

We approach the barrier of Fossil Point.

In this area we see fossilized bone which resembles a whale skull…

…and a whale rib. Several early whale specimens have been recovered from this area.

The contact between the Coos conglomerate above and the bulk of the Empire Formation below it.

GSOCers wait at the Hillary step of Fossil Point.

A shot of the Coos Conglomerate.

Frank Hladky and Dave confer on the beach at Fossil Point.

A view to the south from Fossil Point.

John discusses the Crepidula fossils and the implications of their presence in the Coos Conglomerate.

Laurie finds some good fossils in the mass.

After returning from Fossil Point where we bid John farewell, the group retires to Sunset Bay for a relaxing picnic.

The next few slides are from a reconnaissance trip by Carol, Sue, and Lucy in October 2019 to Sacchi Beach. We parked in the Seven Devils Recreation area and hit the beach on this beautiful day.