With the appearance of yellow in the trees, reminders from the dean to submit the syllabi for the Fall semester, it all points to the end of summer. It also means getting in as much rock-breaking time before school duties resume.
A trip to Arkona - my nth one this year - did not yield up many wow specimens. My goal of finding a full Greenops widderensis has not borne much fruit this year for some odd reason. But I did come close on a few occasions.
This time, I crossed the river to the south bank for the first time (not to be confused with the south pit).
While on the south side of the river, there were some mighty large corals. I left them there since I already have enough coral, and I didn't fancy hauling all that around with me for the rest of the day!
This one is a real heartbreaker. Two nearly complete Greenops (one of which is just an impression), with a third one showing. As readers of my blog already know, the trilobites in the Widder Formation are quite delicate and flaky. Not only does the Widder shale not commonly follow regular bedding planes, breaking anyway they like, but any exposure to rain will cause them to fracture and crumble into little chips. Finding these bad boys intact, and not just endless moults, is rare.
After about two hours on the south bank, there really wasn't much to find. The cliffs were too vertical to risk chopping out benches, and all the fallen slabs had been split and picked over. And so I defaulted to my usual location on the north side of the river, attempting to continue some benches and find some trilobites. While splitting for a few hours, this oddball showed itself. No, not a fossil snowflake, but a hederellid - a kind of branching colonial animal that usually affixes itself to brachiopods and corals (thanks to Don C. on The Fossil Forum for the ID).
Some of the orthocone nautiloids that come out of the Widder can be very impressive as they are usually pyritized. However, they are also very delicate in that unforgiving shale. The pieces below all belong together, but it will be a matter of Humpty Dumpty to put them into their proper shape as some of the pieces crumbled into nothingness when I attempted to clean them. Derp.
The grey shale pieces here all come from a very thin layer I was working where it seemed the Greenops were coming out relatively whole. Following it horizontally, and spot-checking vertically at various parts of the strata, ended up in the trail going cold - just butts, bits, and pieces. Notice the squished one at the top middle...
...So I gave it a quick and careful application of the engraver to pop off some of the matrix. I might risk doing a bit more to see if the cephalon is still there. One has to be very careful in using vibration tools as the trilobite itself is liable to flake off. I might apply some quick crazy glue before trying again.
It was getting close to departure time, so I made my way out of the river and woods back to the north pit, and then scanned the Hungry Hollow Member for little bits. This fairly decently sized Platyceras was only showing a tiny bit of spine from the dirt. Digging it out, here it is in its large glory. Spines on this coprophagous species usually only appear on the juveniles, which can be very tiny (0.5 cm or less!), so it was surprising to see them on such a large one. Here are two other pictures of the same specimen from different angles:
That's about it for this time. Next weekend I hope to be making a trip back in time to the Ordovician - stay tuned!
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?
Now that the course I was teaching is done, and the heavy rains are behind us, thoughts turn back to the hunt. The heavy rain system that lashed a lot of Ontario and western Quebec left a great deal of flooding. Fortunately, not as much here, but the rivers and lakes had been dangerously high, making any collecting near them too dangerous.
But as it is the long weekend, Deb and I got out to Arkona for a five hour hunt. Overall, not a hunt that bagged the best specimens, but we weren't skunked either.
This is the north bank. The photo does not show the proper scale for the bench I worked out. It was already started by someone else, but I was able to lever out two enormous slabs weighing maybe 300-400lbs each. The slabs were partially covered by overburden, so I underestimated their size until I started seeing a crack. But with a lot of grunting and levering with the pry bar, I freed them and rolled them down the hill to be worked on.
Anyone who has worked the Widder shale before knows all too well that one has to go almost quite literally through tons of it to find a full Greenops. Instead, hundreds of moulted bits are quite plentiful.
There are layers in the Widder almost entirely dominate by spirifer brachiopods, but they are trilobite-poor.
Patience and a lot of hammer blows / rock busting can be rewarded. I was able to call first blood on a likely near-complete Greenops widderensis after a few hours working the slabs. Sadly, this one is tucked in the matrix (but can be worked out) and is missing a chunk of its right cephalon.
But it seemed a pretty good day for nautiloids. Pictured above are three Michelinoceras sp.
This one may be a bit more of a challenge to make out, but if you look closely you can see the spiral shape, with a bit of the texture showing in the upper left (the brassy, pyritized stuff). This would be a Goniatites, and a fairly large one for this strata.
And last up: Deb found her complete Greenops (also tucked in matrix, but in better shape than the one I found). On the right is another semi-inflated pyritized Michelinoceras that I'll have to chip out of the rock.
Pictured above is a before and after picture of the nautiloid I found, prepped with a Dremel. Came out fairly well, but this is as far as I dare to take it using an engraver. One day, air scribes and compressors will be needed!
So that's about the long and short of the five hour Arkona trip. Below are some other odds and sods:
Paid a visit to my local rock shop run by two very nice folks. I picked up these two Flexicalymene ouzregui (Ordovician) from Morocco's Anti-Atlas mountains.
A busy brach hash plate from the Bois Blanc Fm fill out in my back nine.
Nice big brach + impression from the same area.
And lastly, another example of Anchiopsis anchiops - pygidium missing its pygidial spike. Lower right I suspect is just a worn and partially buried Eldredgeops rana. Below is a close-up of the Anchiops with some diagrammatic details provided by our Fossil Forum's resident trilobite expert, Scott. "Anchee," as I will call it, is a dalmanitid trilobite, and the way to tell it is by such an incomplete specimen would be the incised axial rings, shown by the arrows in the re-cropped photo below:
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:
The first step is admitting one has a problem!
When Deb and I went to the Home Depot to pick up some foam to seal an area around the pipe, I found myself "wandering" over to the hammer section where I pondered whether to buy a 3' wrecking bar to supplement my smaller pry bar, a new cold chisel with a longer head, and a 4lb blacksmith sledge to go with my regular 4lb sledge. Deb played enabler by telling me I should get them. So I did. But that obliged me to try them out since we are planning to return to Penn Dixie in early October.
So we went to Arkona's Hungry Hollow. And let me tell you that lugging that many pounds of tools and supplies around through a lot of brush and tough terrain ain't always easy!
Unless one wants to be contented with surface collecting of whatever stuff may weather out of the cliff through the process of erosion, the only real and serious way to get at some very nice specimens is to carve slabs out of the wall for splitting. To do that, one has to create a "bench," which is like a long notch in the wall where one can sit and lever out slabs to the left, right, and down.
So we were ready to get started on continuing a bench in the cliff face we found some months back, that we've been steadily extending. I worked a bit on an upper bench that I eventually connected to the lower bench, and created another even lower bench than the one Deb was working on. Having the 3' wrecking bar was making this a lot more efficient (but still back breaking work!). It isn't easy making benches, or even sometimes extending them - there can be a crazy amount of overburden clumped together and slumped over. I've had to go through several feet of the stuff in depth before hitting the actual wall. The other problem can be natural underground springs that leak through the shale, making it wet, muddy, and crumbly. There are plenty of fossils in those, but they just crumble or turn to mud. One has to go deeper into the wall to find dry shale.
Once we were able to cut deep into the cliff face, we found that some of the more trilobite-filled layers were within about a 4 inch area. This picture hardly does any justice to how much rock and overburden was removed. This multi-level bench is aboout 3-4' deep, 7-8' high, and about 15' wide. At a few points I was able to exploit a major crack or fissure to send a few hundred pounds of debris and shale chips tumbling down. There are layers that are just choked with large spirifers. I found a few that had some nautiloids more commonly spread throughout.
Here you can see the bench-build from two different angles. Again, it's difficult to really convey the amount of work we did.
What does five hours of breaking rock get you? Well, for Deb, a full Greenops widderensis. Given the gazillions of moult pieces we keep finding in the Widder Formation, a full specimen is not common. And they are very delicate, so we took several precautions in transport back to the car. But, just to put the spotlight on Deb - this was her fantastic fossil find.
And I'll end his post with just some recent pics as I try to organize some of the recent and past finds. The first is a tray with bays - on the left mostly complete prone and semi-prone Eldredgeops rana; in the centre my accumulation of crinoid stems and sections; on the right a hodge-podge of mostly complete rollers with one Crassiproetus marginatus(?) pygidium since I haven't found a home for it. The final image below is my fully prepped out double roller from Penn Dixie.
Deb and I are set on our first trip to Blasdell, NY's world-famous Penn Dixie site. Two solid days of prying, cracking, and splitting - with hopefully enough fine trilobite specimens to show off, and a lot of matrix to play with in the winter to come.
Since my last post, I managed to make it out to Arkona two more times, as well as the Boler pit twice (finding my second specimen of a Paraspirifer acuminatus). I didn't manage to find anything all that spectacular, so will not be showing more pics of the same stuff you've already seen. But the temps are climbing back down to more comfortable and reasonable levels as autumn makes its stealthy approach ( the leaves, they are a-turnin'!). I am also about to purchase a Dremel stone engraving tool to practice freeing some trilobites that are embedded in matrix. This should be good practice for whatever big chunks of matrix I can bring with me from over the border.
But why not a few pictures in the interim? Here are some select images from the digital microscope aimed at some Arkona finds, and a confirmed Proetus alpenensis(?) - or crassimarginatus(?)
Just a closeup of a Bactrites nautiloid
Tentaculites are neat and taxonomically perplexing!
Goniatites up close and personal, an ammonoid. Not my best example, as I've been pulling ever more out recently.
Say hello to my little friend, the newly confirmed species of trilo in my collection, Proetus.
Why have I included this Eldredgeops rana cephalon fragment in the mix, pulled from the Boler pit and keeping company with a bunch of ne'er-do-well spirifers? Well, because of size. Although this is likely just a moult, this is proof of a rather big boy. Using a kind of averaged out ratio calculation for this species, I figure that the full size would have been about 3 inches, cranidium tip to pygidium tail. I exhausted the rock this one came from in search of just one other piece of the moulting, but to no avail. Alas.
Stay tuned in the weeks to come when I put up our finds from Penn Dixie, and possibly some first attempts at specimen prep! As always, thanks for reading!
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).