Day two saw Deb and I make the 3.5 hour drive to the quarry in Brechin with its diverse Ordovician fauna in the Verulam Formation. We had quite the crew with us, and about four are missing from this picture (actually, five, as Deb is the photographer).
Deb and I were the late arrivals (11:30 am), while just about everyone else had been there probably since sunrise! I actually didn't meet up with everyone until the day was done; they were done at the base of the quarry hacking things out of the blast piles and the underlying Bobcaygeon Fm, while I was busy on the upper ledges doing some surface collecting. I've never had much luck splitting at this quarry.
In about four hours of collecting, I barely made it even a quarter around that one long ledge. I climbed a slightly higher ledge and saw that someone had been there before me hacking some layers out. We use marking tape (or actual markers and piles of stones) to let other people know that these specimens are claimed. It would be considered bad collectors' etiquette to take someone else's claimed finds. We do this when our extraction equipment is parked on the far side of the quarry with an intention to return later. Pictured here is a very long crinoid stem.
Another "off limits" beauty: a damaged but still impressive Endoceras proteiforme, the biggest nautiloid species in this formation.
A typical hash plate to show a snapshot of the marine floor from 450 million years ago.
Although just the impression of a partial pygidium, any piece of this rare trilobite Amphilichas ottawensis is worth picking up. This is a new species for me.
Probably the biggest Prasopora I've found at this site. They are fairly common, but this one stood out for its size.
The nautiloid fragments here can get quite massive.
Assorted goodies here. At the top is a nautiloid fragment, to the left is a trilobite burrow (rusophycus), and on the lower left is a tiny shell hash.
Top row: mostly Rhynchotrema capax - quite abundant in the formation.
Middle row: some gastros, including Lophospira, Fusispira etc.
Bottom row: two pelecypods (from Bowmanville!), two trilobite fragments, and a bryozoan.
Another assortment. Of note in this piece would be the very nice gastros here, but also the Ceraurus cephalon at the lower left next to a 2/3 complete Isotelus gigas and another nautiloid fragment.
Did someone say Isotelus gigas fragments? Here are a few I picked up. The fork-looking piece in the lower middle is the hypostome (a kind of biting mouthpart that appears on the ventral side below the cephalon).
My prize finds for the day: a finger-long gastropod, a small but 2/3 full Isotelus gigas, and two full Flexicalymene senaria rollers. The one on the left is quite inflated and looks like a fat cartoon duck when looking at it from the side.
Day 1 of 3: Craigleith Area
Deb was on vacation time, and so apart from a few beach days and staycation relaxation, we spent three days on the road. Our first stop was Craigleith near Collingwood, and we took the stunningly scenic route through Grey Highlands.
The Craigleith area is filled with Whitby Formation shale overlying the Lindsay Formation limestone. You cannot legally collect from the provincial park, but there are a few very tiny spots left outside of the park where one can split a few shales to find a lot of Pseudogygites moults.
At the park itself, there is a display area of fossils. Pictured above is a fairly large orthocone nautiloid - they got pretty big in the Ordovician.
A complete Pseudogygites latimarginatus. Full ones are exceptionally hard to find as it is more common to encounter enormous hash plates filled with moults.
A fairly representative hash plate of Pseudogygites latimarginatus trilobites and brachiopods. Pieces from over a dozen in this shot alone.
Another representative species of trilobite in the Whitby Formation is Triarthrus. I might be able to free up some of the overlying matrix on this one. It is partially pyritized, although it is tough to make out in this photo.
The pleura of an Isotelus sp. in the Lindsay Formation.
These small, feathery creatures are also common in this shale. These are graptolites.
This is indeed a complete Pseudogygites latimarginatus. A bit crushed and torn, but all the pieces seem to be there. Nice!
Day 2 of 3: Oro-Medonte to Gamebridge and beaverton
After staying in Oro-Medonte / horseshoe valley, we made our way to our B&B in preparation for the big quarry dig on the following day. Although not a fossil collecting day as much as simply a touring of small town Ontario, there were a few rocks around. Deb took lots of pictures of some living creatures like sand pipers, geese, monarch butterflies (so many!), and a cormorant. In Beaverton, we took a stroll along the pier where the sides were shored up by Verulam Formation riprap.
The Beaverton riprap: weathered gastropod hash.
Crinoid hash plate as part of the landscaping toward the old mill park in Beaverton.
We took a walk to Gamebridge's locks system, and then upriver where there were pockets of Verulam limestone. Pictured here as an appetizer to the main event for the next day in the quarry is a brachiopod hash with a piece of Prasopora on the right.
By the same river, a crinoid stalk terminating with half a calyx showing, plus the impression of arms flowing from it. A neat piece!
Last river piece: a hash of mostly brachiopods and bryozoans
Day 3 of 3 (The Main Event)
I was so excited to get into the quarry that I was up at 4 am and left the B&B at around 5:15 during nautical twilight to make the five minute walk to the quarry. I deposited the legal waiver forms, suited up with the hardhat and reflective vests, and poked around to look at the rocks the best I could until the sky lightened up a bit more.
Those who have read my previous post on Brechin's JD Quarry (here) already know the place is incredibly vast and overwhelming. Top left: a large cephalon and genal spine of an Isotelus (fragments abound here, while full ones are very hard to come by). Top right: more Isotelus bits with a Flexicalymene senaria cranidium in the centre. Bottom: typical busy hash plate of assorted crinoids, trilo-pieces, bryozoans, and brachs.
First blood is a prize find: a semi-prone Flexicalymene senaria in the scree at the top level of the quarry. I found it in two pieces and had to stabilize it with crazy glue. Unfortunately, the pin that functioned as the stopper for the nozzle had snapped off, so my glue bottle would be one use only. This piece is still, however, lovely and quite robust.
Eventually, I was joined by Malcolm, Kevin B., and Jabali. We split some new blast piles, and also worked on the new area hauling out tons of rock where Malcolm had found some exceptionally rare cystoids. Sadly, it looked like what he had found the weekend before was an isolated death pool, but it felt good to move enormous slabs of Bobcaygeon Formation limestone. Just to give you a sense of how serious we can be, one piece we moved had to weigh over 700 lbs, and I ended up snapping a steel pry bar. Groar!
I spent the rest of the day trying to cover ground, going through weathered piles of scree along the upper ledges and wandering the immensely mountainous crush piles.
We don't screw around. Jabali snapped Malcolm and me trying to pry this big rock into the pond. We needed to remove from the top down by a good six feet to see if the cystoid layer was going to continue.
Bottom of the quarry, new blast pile. Crinoid stalks can run forever here.
Close up of crinoid stalks.
In situ photograph of a full prone trilobite, Flexicalymene sp. Sadly, as I didn't have any glue left, I wasn't able to stabilize it. The tail piece of this one is now missing.
What survived transport. I might be able to very delicately tease out the left side.
The pustular glabella is poking out at a vertical angle on this piece. Not sure yet what species this is, but will update when I find out. Update: it is looking like I have myself a Calyptaulax callicephalus.
Trilo-pieces. Top right: impression of a pygidium with a margin (to be identified). Centre: Possible Flexicalymene cranidium (to be confirmed - actually no: see picture below). Bottom left: pygidium and some pleurae of an Isotelus.
Well, what do you know? I get to add another species to my collection. Thanks to Don C. from the Forum in planting the bug in my ear that this might be an Achatella achates, an uncommon phacopid trilobite. I just picked off some of the matrix here to reveal the telltale diagnostic features of this species.
Both plates contain partial Ceraurus.
Assortment of trilobite pieces: Flexicalymene, Isotelus.
The big Flexicalymene found at the beginning of the dig is joined by a Flexi roller I found in the afternoon.
This one in need of identification. I have some ideas, but it's just guesswork at the moment.
Some big honkin' pieces of orthocone nautiloid. The one on the lower right I make have to photograph independently as it is the very end of the taper, and with a brachiopod association. The middle one may be Geisonoceras.
A hash plate with a gastropod on the left, and some trilobite pieces throughout.
A close up of this hash. The cranidium belongs to Calyptaulax callicephalus.
Deb found this tiny pygidium. Species needs identification!
I love these high-spired gastropods! The majority of these are Fusispira sp., (and others like Hormotoma and possibly the thin one being Subulites) and the cluster on the lower right with the pinched spires is likely Lophospira sp.
I can't help but to pick up crinoid pieces.
Low-spired gastropods that weather out of the matrix. The one exception is the corkscrew-shaped high-spired gastropod I missed when I took the initial "family photo" of high-spired gastros earlier.
A collection of brachiopods. The bottom two levels are a very typical heart-shaped species - various types of Rhynchotrema.
Odds and sods: top two rows are sponges and bryozoans. Bottom two rows are trilo-pieces.
Before Malcolm left for the day, he gifted Deb and me some fossils. The trilobites I had found and given to him for prep, and I now get to see them in all their expertly prepared glory - my thanks, Malcolm!
This is one of the many pieces Malcolm gave us: segments from a eurypterid (a sea scorpion from the Silurian). The are likely from the quarry in Fort Erie, and so are very hard to come by these days.
Readers of the blog will already be familiar with this Greenops widderensis.
Some Eldredgeops rana I found at Penn Dixie, after Malcolm's masterly touch. The next three images are closeups to show the exquisite detail.
Stay tuned: on Monday I am receiving a gift of fossils from fellow fossil collector Jason Rice, from Utah!
I was able to spend a solid two hours in the south pit at Arkona this past weekend. The rain went from drizzle to downpour, and as mucky and unpleasant as it might make a sustained outing, the weather this season has been so erratic and rain-soaked that it is nigh impossible to plan collecting trips around (unreliable) forecasts.
Still, I made it fairly well in what was mostly a surface collecting operation. The rain brought out the colours of the weathered out fossils very well, making their browns and blacks "pop" for easier spotting.
Weathering out of the Arkona clay, I spotted quite a few of these goniatites. On sunny days, at the right angle, the sunlight makes their pyritized surfaces shine and become easily found; in rain, they show up as dark brown against the Arkona shale's light grey. But these are all full specimens. I've arranged these in ascending order of size, and I was quite impressed to find such large ones when a lot of them tend to be hardly larger than the head of a pin.
Finding full Eldredgeops rana rollers is not unheard of here, but the place does get picked over so thoroughly that they certainly are tougher to find. This roller (pictured at the bottom) had its pygidium sticking up and my eye was immediately drawn to it. As finding disarticulated pieces are the norm, I was pleasantly surprised when it turned out this one was complete. Pictured above it is a small piece of fish plate.
This bumpy piece is a bryozoan. I don't find many of this particular type, and its constellatory arrangement reminded me of when I found that very rare bryozoan at the JD Quarry in June.
The amount of coral one has to sift through can be exasperating, but from time to time one encounters a nice piece worthy of putting in the collecting kit. In this case, a multi-cup example where the calyxes are very nicely articulated.
A collection of Platyceras spinosum. The one on the far left has still retained some of its stubby spines, while the one in the middle is a juvenile. One little fact about these gastropods is that they were coprophagous (they ate poop!), and so it is common to see them fossilized as being a symbiotic attachment to various creatures, particularly crinoids (although I do have one that affixed itself to a coral).
I always manage to pick up little goodies, even if I already have plenty of examples of these already. This assortment is heavily dominated by crinoid ossicles, some with cirra, but if you look closely you will find some tiny nautiloids, brachiopods, and the "button coral" Microcyclus on the upper left hand side.
And, finally, below is a short slideshow of some of the above finds under digital microscope at x75 magnification. In all, not a bad haul for two hours collecting in lashing rain!
Nothing too remarkable about the finds from two trips to Hungry Hollow, the first with Roger, and the second with my Deb. But I may as well post some finds.
On the Tuesday trip with Roger, we did scour the north pit, hacked out some slabs from the north river exposure, and ended by doing some surface collecting in the south pit. On the Sunday trip with Deb, we focused on the south pit since the north is filled with deer flies in the dense bush.
I looked in vain for the other half. This was worked out of the coral layer of the Hungry Hollow member.
Deb splits a coral to get a look at the structure inside.
A typical hash plate from the Hungry Hollow member, the layers without as many corals. You can see some trilobite cephalons in there.
Brach-encrusted shell pavement from the Arkona Formation. Found with Roger on the north pit part of the trip.
Not entirely sure what this is yet (to be updated). Could it be a Basidechenella trilobite glabella? About an inch long.
A pelecypod from the coral layer.
Lots of stuff going on here. Trilo-bits, a possible fish plate, tons of crinoid bits, a Platyceras conicum (lower left), brachs, etc.
Next up are a few of Roger's pictures and finds after he cleaned them up:
Roger snaps a picture of me up in the bench.
We were finding a few of these pyritized orthocones in the Widder shale. Not in itself a rare thing, but this one is intriguing.
These Tornoceras arkonense really clean up well! You can pick them out of the Arkona shale, but they also come out a bit bigger in the Widder shale. One must just be on the lookout for a bit of metallic glint, suggestive of something pyritized - and it could be one of these.
This one is a bit of a mystery. It is about 7 mm, but has some strange suture patterns. We're not sure which of us found this in the Arkona Fm, but that is immaterial. It is not a Tornoceras, and neither of us can find this ammonoid described in the usual places (such as the Stumm and Wright checklist or on the UMMP database). Could this be a new and undescribed species?
Deb and I made the four hour drive up to the east side of Lake Simcoe to dig at a quarry in Brechin. This was my first time working an active quarry, and it was exciting (and potentially fairly dangerous if you don't properly observe some common sense and safety precautions). It was about a day and a half of rummaging through the rocks on mostly sunny and hot days. But we didn't come away empty-handed!
Deb and me ready on our first day. We arrived shortly after 2 pm. Francie from the Ohio Dry Dredgers and a few of their members were just finishing up. They had just come up from Penn Dixie, and we thank Francie for snapping our picture.
I cannot stress enough that this is an active quarry with regular blasting and areas that are not entirely safe, so there is no messing around here. Full safety equipment (steel-toed boots, hard-hats, and reflective vests are absolutely mandatory), and it requires signing a legal waiver before entering the site. On the right is the entrance.
On the left is just some of the mountainous crush piles. To the right, I'm hauling our wagon full of gear to the uppermost tier flanked by some gullies.
This is a view from the second level overlooking a part of the pit. For a sense of scale, a person standing at that back wall would look little bigger than a dot in this picture. The machines below are quite large. The stratigraphy is mostly Verulam Formation from the Ordovician, with some Bobcaygeon Formation now being dredged out from the base.
Again, a bit tough to make out scale, but the drop here is precipitous. That rock near the top could fall at any time, so it is generally a good idea not to be poking around directly at the base of any of the walls. The usual rule is to keep about no closer than a 45 degree angle from the top of the wall. A lot of loose stuff out there just waiting for any tremor to send it all down - and no hard hat is strong enough to save you from a few hundreds tons of limestone crashing down!
A typical hash plate rich in crinoid and other bits. I tend to either photograph or take home interesting hash plates, and particularly from places I don't get to collect from very often. It gives a sense of the marine bed.
Another hash plate. The Verulam limestone itself is mostly storm-tossed debris as opposed to just the quiet deposition of organisms and sediment over time. In some rocks, you can see the violent wave/ripple of mud having had churned everything.
Two more hash plate with some rich biota. If you look very carefully toward the upper right of the second one, you can pick out the tail piece of a tiny trilobite.
One of the hash plates I brought home of a storm depost of brachiopods and some trilo-bits.
Last hash plate pics, I promise! These are just a few I brought home. The one on the left that is brown fell from the uppermost part of the Verulam and has a good collection of gastropods and a few brachs.
A few members of our crew. From left to right: Roger, Malcolm (with the rock saw), and me. Deb took some video footage of Malcolm in action cutting out a nice multi-plate crinoid slab. Malcolm has been a regular at this quarry for several years, and there is very little he hasn't yet found in terms of the large faunal variety present here.
Malcolm's infamous no-fooling-around rock saw beside a multi-plate of crinoids (picture by Malcolm)
I've been tasked with turning the rock over so that Malcolm can continue his cut to free the crinoids (picture by Malcolm).
Some high-spired gastropods (Fusispira sp) and flatter ones. These weather right out of the rocks. New material depends on the quarry to be blasting out new stuff. Deb and I found that splitting the blocks was not getting us very far - most of the stuff to be found is either weathered out, or appears solely on the exposed parts of the rock. The rock itself alternates between thinly bedded mudstone/shale and very dense encrinal layers. Splitting the mudstone usually had traces or were just blank for us.
Malcolm found this cystoid (Pleurocystites?), and was kind enough to give it to us. I'll try to confirm the species when I update this post.
Crinoid stalk. Certainly not the longest you can find here!
Closeup of a branching bryozoan (Stictopicorella?).
Malcolm tells me that this is a bit of rare one at the site. I found this in the fallen materials on the second level. It is now been confirmed by veteran fossil collectors Kevin K. and Joe K. as the bryozoan, Constellaria - and this may be only third one ever found at this site.
Closeup of a trilobite I pulled from the bottom level. I was really coming for trilobites on this trip, and I was not disappointed. The first one I found in the upper level gullies was a Flexicalymene senaria roller, but this one is a prone and partially/maybe disarticulated one?
One of the most common trilobites in this formation is Isotelus, but full specimens are a bit tricky to find. Just about every rock has bits of them. On the left is a collection of tail pieces, with the one on the extreme left a fairly large (4 inches wide) example that Deb found. On the right are some other pieces, mostly of a genal spine, a hypostome (the mouthpiece, which looks a little like a wrench head) and some head pieces (cranidia).
This I found on the second level: a ventral view (underneath side) of an Isotelus - or what remains of it. You can see the hypostome.
This is a virtually complete Ceraurus missing only its pygidial spikes. It is currently with Malcolm who will be prepping it for me.
Trilobite rollers! I had very much wanted to find a complete Isotelus, and I was not disappointed. The "Kermit" looking one on the left is virtually complete and found lodged in the strata on the second level of the quarry. The one of the far right is a Flexicalymene that I had found minutes upon exploring the site, and the middle one is a Ceraurus sp.
A closeup of the middle one.
I still have a bucket of stuff to go through, and some IDs to put on the finds. In all, it was a fantastic and exciting trip. My thanks to Malcolm for being our gracious and knowledgeable host.
The site boasts a heck of a lot of variety for trilobites alone. Below is a table of identified and described species found in the Verulam Formation by B.A. Liberty (1969) Paleozoic Geology of the Lake Simcoe Area, Ontario. Geological Survey of Canada, Memoirs 355. Since then, Ludvigsen (1979) describes a few others, including Amphilichas (a pygidium of which Malcolm found just this weekend, and is considered a rarity - and never found whole).
Update: I just performed a bit of light cleaning of the rollers and snapped slightly better pictures of them here:
I've been meaning to photograph some of the great stuff my fossil comrade from Connecticut, Tim, kindly gave me after our big dig in Penn Dixie
First up on the top left are specimens of the Devonian gastropod, Glyptotomariz retispiralede collected from Deep Springs Road, Earlville NY. To the top right is another from the same area, Grammysoidea arcuata. On the lower left are Bembexia sp. gastropods from Morrisville, NY. To the bottom right from Deep Springs Road is Paleozygopleura hamiltonensis
These lovely fish plates are Redfieldius gracilis from the Shuttle Meadow Fm (Jurassic).
These ferns come at a premium now, as they were collected at St Clair, PA where there is no permitted collecting at the site anymore.
The lighting and the faint impressions these generally leave may make this harder to make out, but these are partials and pieces of the fish, Diplurus newarki - a fish my comrade Tim has been studying and collecting for 20 years.
These are coprolites. Yes, fossilized poop. On the left is a coprolite (likely a reptile extruded this one) from the Triassic, while the ones on the right are from the Jurassic. We can learn a lot from studying coprolites, such as diet and environment.
I also have a few pieces of Otozamites latior that do not photograph well. Tim was also kind enough to provide me with two trilobite specimens I did not have (see last blog post).
Shifting gears in the same post, I took a trip to my local honey hole and was entirely skunked. At the very least, I got to be within 7-8 feet of a fairly trusting and majestic bird. I apologize for the poor pixel quality - I only had my iPod with me at the time, and I needed to zoom in a bit as it would have flown away had I approached any closer:
So the afternoon was spent at Hungry Hollow where I collected small bits. The river was too dangerous after all the rainfall to risk going to the usual spots, so we hunkered down in the south pit and plucked weathered stuff out of the Arkona Fm mud-shale. Although I have tons of this stuff, I can't help but to continue picking it up. You never know when someone might want some of it as a gift.
Typical fare from Arkona: an array of crinoid bits, some Aulopora, brachs, Microcyclus ("button coral"), tons of Bactrites, and on the right edge in descending order of size, Tornoceras (or is it Goniatites? - I'm not a cephalopod guy).
Below are some microscope shots to bring out details at 75x:
This past year has been precedent-setting for fossil collecting as it has also meant a staggering number of new and fascinating specimens added to a collection that seems to have colonized a lot of space in the house. No fewer than 8 trips to Hungry Hollow, countless trips to my nearby “honey hole,” some visits to the Ottawa and Rideau rivers, and 2 fabulous multi-day adventures at Penn Dixie. Deb and I have found numerous trilobites, including several full prone Greenops widderensis, well over a hundred Eldredgeops rana rollers and prone specimens (this in itself a major change from a few years back when I hadn’t bagged even one full specimen), and some fairly large and nearly complete Pseudogygites latimarginatus. And that’s just the trilobites. Several new types of corals, gastropods, brachiopods, crinoids, and cephalopods were also added - and even a fish plate. So many were gathered, in fact, that I was glad to be able to sell off some excess in support of the United Way campaign at work.
The above trilobite, Flexicalymene ouzregui, was my first fossil purchase, a gift to Deb for all her great work and finds this past year. It is Ordovician in age and from the Atlas Mountains in Morocco.
Coral of the Year prize is tied with this specimen and one acquired from a trail. Both are Devonian
A lot of contenders for Assemblage of the Year, but the usual stuff from Arkona can take a backseat this time. It is a tie between this gravestone-sized block of black shale from Ottawa with plenty of Pseudogygites latimarginatus trilobites (and nautiloids), and an assemblage of Eldredgeops rana from Penn Dixie
Among a lot of brassy-coloured Goniatites and sundry other Devonian goodies, this slightly pyritized nautiloid from the Widder shale weathered out whole and not in its usual crushed state in the shale, earning it Cephalopod of the Year.
It was a bit of a challenge to settle on Gastropod of the Year, what with some neat high-spired specimens, but let's give the honour to my specimen Naticonema lineata from the encrinal layer of the Arkona Fm.
Although I did find a crinoid "bulb," I'm giving this pyritized beauty from the Arkona mud-shale Crinoid of the Year even if it is just a stem.
Amidst hundreds upon hundreds of brachiopods collected this year, including giant spirifers and the like, I could have copped out and said all of them are deserving of the honour of Gastropod of the Year, but let's opt for this specimen that preserved the umbilicus.
And the only fish fossil contender of the year, a confirmed fish plate from the Widder Fm
Contenders for Trilobite of the Year are legion. Instead of simply picking the biggest or most "perfect" specimen, this year is a tie between a Greenops widderensis that Deb found in the brittle Widder shale of Arkona, and an Eldredgeops rana that had been twisted and wrenched into an odd configuration, found at the Hungry Hollow Mbr of the Widder.
What follows are some odds and sods I hadn't got around to posting. Until the 2017 collecting season!
A steady six-hour stint at the Hungry Hollow site in Arkona was a productive outing. I began in the north pit and found an Eldredgeops Rana roller in under ten minutes, but the fossil gods only pay out at the beginning or end of a trip, or not at all, so the rest of the trip was dry when it came to any other rollers. I plucked it from the ground near the big mound of piled up Arkona "shale."
Here, your intrepid fossil adventurer is poised to begin the day with his new Estwing rock hammer and assorted gear.
It wasn't too hot, but it could get buggy in some places. After I ventured through the woods to get to the two main river exposures, that was when the biting deer flies found their new meal. I could only work the exposures of the Widder formation for about an hour before it became intolerable. I hauled out some modest chunks of Widder shale from the wall, but it was awkwardly placed a little too high from the scree, and pretty much vertical with no convenient handholds. So it was back to the south pit for me.
Here's a fairly representative assortment of some of the small pieces I pulled from the Arkona layer. The first two in the first row are very likely fish armour plates. Second row: crinoid sections/columns of varying types. Third row: two goniatites followed by a bactrites. Fourth row include three trilobite roller fragments, three platyceras in ascending size, a brachiopod, and a brassy-coloured mussel. Fourth row: two button corals, my lovely roller (pictured alone below), and just some odds and sods including a British 5p piece found in the mud.
Working the south pit floor is where you're most likely to encounter scattered, weathered out bits from the Arkona layers. There are plenty of brachiopod shells, mostly poorly preserved, cephalopods, and crinoid stalks like the one pictured above. The lustre of this particular one shows a heavy degree of pyritization, which is the first stage to its rusting to nothingness if left out to weather any further.
And here is my fully intact roller from the side view. Not terribly large (a little over a centimetre wide), but with no flaws.
A closeup of the Arkona sectioned off with a crinoid stem (indicated by the head of the rock pick). I got talking to Rick who comes often to dig through these layers in search of intact crinoid crowns. The trick is to dig past the "blooms" that form when the exposed mudstone/clay goes through the wet/dry cycle and bakes (this stuff was actually extracted to make drainage tiles). It can be tricky to work with given its clay-like softness and no bedding planes, and the state of preservation is quite fragile. Much of the Arkona layers are sparsely or non-fossiliferous, as they are basically composed of mud deposits with very thin fossil layers and shelly limestone pavement. A very interesting explanation of how stormy these seas were in reworking the sea bottom environments (and the short growth windows due to poor oxygenation), and how it impacted growth among the benthic creatures can be found here. My thanks to TFF member doushanto for the reference.
Speaking of references, this is a generalized stratigraphy of the Hamilton Group, which includes the "big three" in this area. In ascending order they are the Arkona (more mudstone than shale), Hungry Hollow formation, and the Widder formation which, in some points, does not reach its top end due to weathering. This image is from Wright and Wright (1961) "A Study of the Middle Devonian Widder Formation in Southwestern Ontario" available via the University of Michigan. Read it here. Just a few remarks: the units listed here that seem to form ledges are generally sparse or non-fossiliferous and are largely erosion resistant. Some of the best places to hunt for Greenops trilobites would be either in the units under those ledges, or occasionally above them. They may appear in other units as well, but you'll be more likely to find them in death assemblages (thanatocoenosis) or by other forms of deposition. A good resource if you're looking to have a checklist of the biota in each of these formations in the Hamilton Group would be Stumm and Wright (1958) "Check List of Fossil Invertebrates Described From the Middle Devonian Rocks of the Thedford-Arkona Region of Southwestern Ontario" - although this is a foundational resource, it could use a serious update to reflect some of the newly discovered species since then.
Deb joins me after a day at the cottage, going through a pile of recently carved out Arkona mudstone. It just comes apart in your hands.
And some other odds and ends of the day. Top right is a busy vermiculated bunch of crinoid stems from the Arkona, while the large piece on the right is a bit more firmer substrate of the same. Bottom left is a larger shell, and to its immediate right are two Greenops trilobite tails from the Widder. I didn't spend as much time in the Widder due to the biting flies, so no full specimens were found.
I'm abandoning the inconvenient and awkward episodic approach to detailing fossil adventures by going blog-style. I have no plans to migrate previous (and interesting, I assure you!) content to the blog, but you can access the whole list here. Three years worth of finds.
Since last year, I was able to take advantage of the El Nino temporary thaw to visit Arkona in January, revisited in late April (as well as my favourite pit near my house), and once again for a good three-hour stint in the south pit (here and here). Deb and I have much more focused on the north pit end, navigating the more treacherous terrain of fallen trees and slippery clay along the roaring river, and finding a gallimaufry of Greenops boothi trilobites in the fallen Widder shales. My recent visit was a poring over the exposed Arkona Formation and the overlying Hungry Hollow.
Here are just a few of my finds from the May 15 outing. Deb and I will be making a trip to Ottawa next week, and I hope to reconnect with my old Billings Formation friends from childhood, so fingers crossed to add a few pseudogygites to my collection. I'm playing catch-up, so some of these photos will include a few London finds.
Widder shale is VERY brittle, and so full specimens of the trilobite Greenops widderensis is a rare delight. Unfortunately, bedding planes are not so cooperative, and so parts of the trilobite got "stuck" in the impression to the left.
Like I said, full specimens of old Greenops are hard to come by. Pictured here is a smorgasbord of mostly tail pieces (pygidium) and a few thoraxes. What I love about this species is the saw-tooth butts. These were definitely a defensive adaptation to increasing predation, alongside their tough chitin carapaces and ability to roll up into a ball like their cousins Eldredgeops.
Just some interesting pieces: brachiopods and a gastropod. A closeup of the specimen on the far left appears below:
This is the underside. Pardon my fingers.
Spirifers (brachiopods). I must have buckets of these now. I should start selling them. Want to buy a fossilized shell from 350 million years ago? I got you covered.
Closeup of some Greenops widdernesis fragments. Note how mineralization conditions may differ to give them a different coloured "patina." This is like a Paleozoic Benetton ad.
This was at Boler. A clam, but a fairly large one compared to many of the specimens of its kind. As you can see, I have yet to graduate to a bona fide geological hammer.
On my recent trip to Arkona, south pit, I just can't help picking up crinoid bits. Here you can note their diversity.
Here is an assortment of cephalopods (bactrites) I plucked from the Arkona Formation. In the sunlight, their brassiness shines.
An assortment of shells.
Miscellanea. We have bryozoans, two button corals (Microcyclus), platyceras, and what I suspect on the far right top row to be a placoderm plate. On the bottom row a lot of fragments of the trilobite Eldredgeops rana.
Below: Ok, it's been a few years of ridiculously long hours in search of another Eldredgeops intact roller. I mean, a lot of people pick the place over. And it is not like I don't know what strata to target, or that I lack the eyesight or discernment (I've been known to pick out a single pleura from a distance of almost a yard, such is my hawk-eye ability for finding trilobites). After three hours, I was just about to give up. With five minutes until I would get picked up, I decided to just take a desultory and defeated look at some tiny outcrop of fragments. I figured it would be like the rest of the day ("coral, coral, coral, coral, crinoid stem, coral, coral, coral, brachiopod, coral, coral, coral x 1,000"). Up this point, I was only pulling out tiny fragments, mostly embedded in the wildly bioclastic Hungry Hollow rocks. I skipped the paper shales with their Leiorhynchus ad nauseam, ignored the sparsely fossiliferous parts of the HH Fm that never weather out and jut out like prows, knew better than to go digging in the Arkona FM slick grey clay, and turned my nose up at the dull (to me) bioturbated stones with all their worm burrows. Otherwise it was rugose coral everywhere. I really wish I could temporarily "delete" those coral to get a better view of other fauna. Anyway, just like when I found my first roller back in 2013 just minutes before I left, so I found this twisted fellow. The funny thing about trilo-hunting is that it seems an odd phenomenon that so many of us make our best finds either at the beginning or end of the trip. Anyway, here are some different angle shots to show how twisted this Eldredgeops is. It is *almost* complete (just missing the right bit of cephalon/eye and a tiny bit of the pustular glabella).