Archive for the ‘Geology’ Category

Sponge Encrusting Worm Tube Encrusting Bryzoa

June 10, 2010

At a crinoid garden that I have been working for a couple of years, I found this curious example of an epibiont on an epibiont.

First, a trepostomate bryozoan found its home, then some cornulites worm tubes found the bryozoan inviting.

Finally, the sponge.

When it was alive, it had to have been pretty cool looking with the worms sticking out of the sponge.

Width of photo about 3cm

Mag x10

You know the scale

Since, it was found at one of my crinoid “gardens”, here is a double from the same locality. I have pulled about 50 crinoids from this site(too lazy to check my notebook), and the Archaeocrinus sp. out number Pychnocrinus sp. by a substantial majority(again, too lazy to check my notebook), So these are probably Archaeocrinus sp.

Many of the crinoids at this site appear to be weathered, but they are from fresh exposures??? They are found in a thin lens of mudstone within a calcarenite/calcirudite. They are early Late Ordovician. Some researchers postulate that the abrupt changes in facies in the Central Kentucky region is due to weird structural crap associated with tensional forces at the close of the Taconic Orogeny to the east.

So, that leaves me wondering… were these critters left high and dry in their shallow lagoon/inlet by a regression, and then covered by a transgression??? It seems plausible. They could have laid there for months, or longer, since there were no land critters to pick at the carapaces.

Do you have another scenario??? Let me know.

Anyway, here is the double.

Width of photo about 10cm

Here is one that I have shown before. It is from a fresh exposure, so it can’t be weathered.
Width of photo about 6cm

Structural Inversion and the Origin of a Late Ordovician Carbonate Buildup:

The Ordovician Earth System

Correlations Across A Facies Mosaic…

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Sponges

June 3, 2010

Dave, over at Views Of The Mahantango, put a post up yesterday describing some sponges(stromatoporoids) that he had found from Devonian rocks of New York and Kentucky, and some Silurian rocks of Pennsylvania.

This post will add to his description.

Stromatoporoids are peculiar, and poorly understood, sponges(Porifera) that evolved in either the Cambrian or Ordovician. Some experts classify some Cambrian archaeocyathids as stromatoporoids, but that classification is tenuous. They became extinct during either the Devonian or Mississippian… then re-appear in the Mesozoic forming reef building communities, again.

The Paleozoic forms lacked spicules-common to other types of Porifera.

I said that they were peculiar.

As Dave noted in his post, they formed massive reefs in the Devonian. Sometimes, tens of meters thick. Though, in the Ordovician, the reefs are less massive. Also, they were restricted to warm tropical waters near the equator. The Late Ordovician glaciation on Gondwana appears to have substantially reduced the numbers; since they lived in the shallow tropical seas, their habitat was decimated by the regression associated with the ice advances.

Sometime around Devonian/Mississippian time, they became extinct… but then re-appeared in the Jurassic with spicules.

Confused? Well, that makes two of us.

Most of the uncertainty is the result of very little research on stromatoporoids other than their paleoecological relationships. For the most part, their phylogenetics is unknown.

A few photos of some Ordovician stromotoporoids. All are from the Millersburg member of the Lexington Limestone, and found in Fayette Co. Kentucky(though, from two different localities). As always, click on image for bigger version.

All of these, with the exception of one, were left in the field-they are too big to lug around, and take up too much space.

Some that had fallen from the outcrop.

One that I have brought home.

Same as one above showing the concentric layering.

Another peculiar sponge that I find in the local rocks is Solenopora. Like the stromatoporoids, it was also mis-classified for years. Originally, the chaetetids were classified as tabulates.

Recently, Solenopora was re-classifed as a chaetetid, again no spicules. Solenopora aren’t common in the rocks of the Lexington, so when I find them, they find a new home in the cabinets(too, they are smaller).

Again, these were collected from the Millerburg mb of the Lexington Lm in Fayette Co. Ky.

This first I re-sized for some reason??? But you can get an ideal of what it looked like.

Width of photo about 10 cm.

Close up showing an orthogonal view of the pillars(mag x50)

To learn more about these peculiar critters, here are some good links.

Paleos Metazoa: Porifera -follow the links.

Systematics of Porifera– again, follow the links.

Or, you could ask Mr. Google.

Kill Pill Vol. 2

May 28, 2010

BP has been dumping kill mud for a couple of days, now, off and on, and the well still flows. Granted, the initial dump might have been merely an attempt to understand the parameters of the system, and what it could withstand, but it appears to have been a failure. Contrary to initial reports of an admiral in Louisiana, the pill didn’t overcome the pressure of oil and gas escaping the system. BP estimated that it would take 1300 bbs of kill mud to fill the bore; they had 90,000 bbs on hand, and they stopped pumping after 16,000 bbs had been injected. Apparently, the vast majority of the mud was escaping through the riser, so they decided to re-assess(???).

When they started pumping again, they decided to go with a “junk” shot in an attempt plug some of the openings. The “junk” consists of pieces or rubber, small spheres, pieces of rope…, and whatever else might help to seal, or reduce, some of the leaks. The ideal being that the kill mud will have more area to “push” against, and hopefully, push the oil and gas down to the base of the well. If successful, the weight of the mud will effectively balance formation pressure, and then cement will be pumped to permanently seal the well.

BP has said that the process will take 36 to 48 hours before they will know if the process is successful, and that it appears that it is working, we are coming up on that time. Some engineers and geologist knowledgeable in petroleum extraction have described the process as “pissing in the wind”.

Looking at the feed from the ROV, one notices the white-snow like-material floating down. It leaves me wondering if it is gas hydrates forming from escaping hydrocarbons, if so, it doesn’t bode well for this attempt at kill the flow.

At about 09:15 this morning, something dramatic happened. Was it a “junk” shot, or was there some kind of failure. Check out the video at about 16 secs, and then at 1:14:

If this fails, they will next attempt to cut the top of the riser and install the Top Hat. It will be fitted with grommet to fit tightly over the top of riser. While, this won’t eliminate all of the oil and gas that is escaping, it should catch most of it… if all goes according to plan.

Here is to hoping…

Kill Pill Vol.1

May 25, 2010

Tomorrow BP will attempt to “top kill” the well that is spewing-who knows how much-oil into the Gulf of Mexico(GOM). BP estimates somewhere around 5000 bbs/day are escaping from the collapsed riser and blowout preventer(BOP), but researchers at Purdue, using estimates from live feeds, estimate the flow somewhere between 40000-100000 bbs/day.

The Purdue results appear to be high; top producing wells in the GOM generate about 50000 bbs/day. This well’s location is in an area(Miss. Canyon Block 252) of the gulf that isn’t as productive as some other areas. So, I tend to accept BP’s estimates… within a margin of error, of course.

The “top kill” procedure involves pumping drilling mud into the BOP in pressures greater than the escaping oil and gas. The ideal is that the pressure from the pumps combined with the weight of the overlying column of mud will displace the hydrocarbons in the production string of casing from the well head to the base of the well, and then fill the casements-effectively blocking the leak. Cement will then be pumped into the string to seal the well… if all goes according to plan.

And, therein is the problem-nothing has gone according to plan. BP, and others, have speculated that the reason for the initial blow out was that a poor seal in the contact between the production casing and the protective casing at the base of the well. Apparently, the blow by was noted by engineers when mud pit volume increased out of proportion-well logs indicate that twice they stopped pumping mud in the two hours before the blow out!

In yesterday’s press briefing, BP noted that in finding cause of the blow out, the “investigation is focused on the following seven mechanisms.”

1. The cement that seals the reservoir from the well;
2. The casing system, which seals the well bore;
3. The pressure tests to confirm the well is sealed;
4. The execution of procedures to detect and control hydrocarbons in the well, including the use of the BOP;
5. The BOP Emergency Disconnect System, which can be activated by pushing a button at multiple locations on the rig;
6. The automatic closure of the BOP after its connection is lost with the rig; and
7. Features in the BOP to allow Remotely Operated Vehicles (ROV) to close the BOP and thereby seal the well at the seabed after a blow out.

Regarding 3 above: rumor has it that a well known, and very expensive geotech firm was on the platform to do cement-bond logs, and that in a hurry to get off site(so the completion crew could move in???), BP’s top guy on-site put a stop order on the c-b logs. One thing is known-the geotech firm confirmed that they pulled their people 6 hours before the blow out- which was 14 hours after the final cement job for the seal started pumping.

There are other rumors floating around that the well was “kicking”… hard, and that for that reason, a “dump kill” was recommended hours before the blow out.

I guess that we will find out in Congessional hearings.

There are a lot problems with the “top kill” plan. Some have speculated that the mud, under those pressures, will fracture the formation, and that this will lead to greater flow at the base. Fracking wells is a common procedure to increase production in reservoirs, but as the sediments in the gulf are very permeable(around 30%), and barely consolidated, it doesn’t seem that if the formation does frak, that it would a problem.

Though, a real possibility is that blockages in the string will force the mud out the BOP, eroding what constraints are inhibiting the flow. Another danger could be a blow out in the containment string near the surface… if the seals are bad, and there are blockages, the mud could force its way into the containment nearer the surface where that part of the string doesn’t generally encounter those types of pressures.

BP estimates for success are 60-70%. If unsuccessful, a “junk” shot will be attempted in which various sized rubber balls will be injected into the system; If that fails, an attempt will be made to cut off the top of the damaged BOP and affix the Lower Marine Riser Package(Top Hat) to the clean surface.

I wish the crews luck tomorrow. Hopefully, by tomorrow night the well will be sealed… but I doubt it. From the opinions of engineers and geologists, that I have read, this thing might be flowing until the relief wells are finished in the late summer.

Note: I am not a petroleum geologist, and I do not work in the industry. If I have misconstrued anything, or is there is more to add, let me know in the comments.

Deep Water Stuff

May 17, 2010

The Ordovician of New York has been a fascination of mine since reading of C.D. Walcott’s discoveries, there, many years ago. A couple of years ago, I was granted the opportunity to visit a newly discovered lagerstatten in the Lorraine Group of Upstate New York.

The site was discovered by an amateur paleontologist from the region. In his quest to better understand the geology and paleontology of New York, he found the site that we visited, and several others that have produced stunning soft-tissue preservation of annelids and arthropods.

The Martin Quarry is located in the Whetstone Gulf Formation of the Lorraine Group in New York about 60 or 70 km north of Beecher’s Trilobite Beds. The rocks were deposited in a deep foreland basin that formed as a result of the Taconic Orogeny during the early Late Ordovician. The Late Ordovician was a time of intense tectonic activity on the Laurentian continent. As a result, the rocks of the Lorraine are characterized by sequences of turbidites.

It is within the turbidites that the exceptional preservation of the fossils are found. Bedding planes reveal hash plates with numerous partial trilobites-among other critters, but within the beds, whole critters can be found. And, if one is in the right horizon, the critters soft parts are preserved in pyrite.

Some photos:

After picking up a prep guy(one of the best in the field) at JFK, we got stuck in a traffic jam on the Tappan Zee… at 03:00!

Curiously, crinoids are absent from the locality, but they were somewhere, nearby.

The first thing that I saw when walking up to the outcrop was this lovely cephalon. The site is known for its Triarthrus fauna, and I was expecting it, but… this was the first Triarthrus that I had seen in the field! I was stoked!
photo about 15cm wide

A photo of me chopping away.

A photo of My Good Friend Who Is A Dog chillin in the creek.

A cutie(photo about 10 or 12 cm wide)

photo about 2cm wide

photo about 1.5 cm wide

Some kind of reptile… I might add, this guy shouldered(literally) a couple of tons of shale in an attempt to protect his finds, only to put on the gloves for this critter.

Probably, 75-100 partials on the slab.

Lots of partials and some other things, too. It appears that there is at least one calymenid free cheek, and a Sowerbyella brack. width of photo about 25cm

A nice ventral that is now part of the Peabody Museum collection

The guy that found this quarry developed a revolutionary an innovative technique in the preparation of pyritized soft tissue recovery… his methodology, at first, seems counter-intuitive, and maybe destructive, but his results are telling.

Further reading and references:


Beyond Beecher’s Trilobite Bed: Widespread pyritization of soft tissues in the Late Ordovician Taconic foreland basin

Farrell, et. al. 2009

Pyritization of soft-bodied fossils: Beecher’s Trilobite Bed, Upper Ordovician, New York State
Briggs, et, al. 1991

\Turbidite depositional influences on the diagenesis of Beecher’s Trilobite Bed and the Hunsrück Slate; sites of soft tissue pyritization
Raiswell, et. al. 2008

EDIT: to add photos

Correlating the Ordovician of Laurentia

May 12, 2010

Recently, in an email exchange with another Paleozoic geek, we discussed the relationship of the stratigraphy of Ontario with that of Kentucky. The discussion centered around the Veralum Formation up north(Canada), and which units of the Lexington Limestone(Kentucky) share a temporal equivalence, i.e., which beds of the Lexington were deposited at the same time as the Veralum.

It has been know for some time that the Bobcaygeon Fm. of Ontario was deposited at about the same time as the Curdsville mb. of the Lexington Lm. Further, the ecology and the environment was very similar; many of the same rare echinoderm/trilobite assemblages are found in both beds.

Outside of the carbonate build-ups of Central Kentucky, that time in the Ordovician represented a transgressive sequence, so one would assume that the relationship could be established by looking at the stratigraphic record for both areas.

Mitchell, et. al. in 2004 did just that. Proceeding from the works of previous authors, they studied a prominent meta-bentonite(the Millbrig K). Since, ash falls are distributed over a large region, could they be correlated?

The abstract:

    The Ordovician (Chatfieldian) Millbrig K-bentonite Bed is a key stratigraphic marker horizon that is regionally synchronous over much of eastern and central North America. This prominent marker is an independent source of correlation among the major chronostratigraphic and sequence stratigraphic units in this region. The general stratigraphic position of the Millbrig Kbentonite has suggested to some authors that it is identical with the Hounsfield K-bentonite at Dexter, New York (the traditional type area of the Middle Ordovician, or Mohawkian Series in North America), but previously available geochemical and biostratigraphical evidence has been insufficient to confirm this correlation. Analyses of apatites and melt inclusions in quartz phenocrysts from the Millbrig K-bentonite at eight localities in Kentucky, Missouri, Virginia, and Pennsylvania and the Hounsfield K-bentonite at its type locality at Dexter, New York, using high-precision electron microprobe analysis techniques shows that the Millbrig and the Hounsfield have identical apatite and melt inclusion chemistry indicating a geochemical correlation. This correlation is supported by conodont biostratigraphy, and d13C isotope chemostratigraphy. The new data demonstrate that the Millbrig K-bentonite, and therefore the base of the Chatfieldian Stage of the North American Mohawkian Series (by definition), lies very close to the base of the traditional Rocklandian Stage of New York. Furthermore, the Millbrig Kbentonite Bed lies in close proximity to the base of the Taconic supersequence over much of the Midcontinent region and in particular lies just below the M5 sequence boundary recognized in Kentucky and Tennessee. Our results permit extension of the Chatfieldian sequences into New York State and southern Ontario, and contributes to the resolution of the long-standing uncertainty about the position of the base of the Trenton Group in Ontario. Furthermore, viewed in a broad context of regional stratigraphic relations, we conclude that our results suggest that the persistent correlation difficulties reflect diachronous effects of widespread changes in oceanographic circulation patterns that emerged during Taconic Orogeny. Finally, regional differences in the timing and character of sequence bounding surfaces and facies similarities summarized here suggest that the causes of relative sea level change during the Chatfieldian may have been primarily tectonoeustatic mechanisms.

One of the real gems of this paper is the correlation chart. Using the ash falls, they correlated the rocks from Illinois through Kentucky, and then up through the foreland basin of New York.


So, pertinent to the email exchanges, it appears that the Veralum’s equivalent in Central Kentucky is the Tanglewood and Millersburg members, and some basal units of the Clays Ferry and Kope Formations in the Outer Bluegrass region.

Further reading and references:
Discovery of the Ordovician Millbrig K-bentonite Bed in the Trenton Group of New York State: implications for regional correlation and sequence stratigraphy in eastern North America
Charles E. Mitchell, et. al.(2004)PDF

Blackriveran carbonates from the subsurface of the Lake Simcoe area, southern Ontario: stratigraphy and sedimentology of a low-energy carbonate ramp
Jonathan L. Grimwood, et. al.(1999)

USING GIS TO ASSESS THE BIOGEOGRAPHIC IMPACT OF SPECIES INVASIONS
ON NATIVE BRACHIOPODS DURING THE RICHMONDIAN INVASION IN THE
TYPE-CINCINNATIAN (LATE ORDOVICIAN, CINCINNATI REGION)

Alycia L. Stigall(2010), et. al.

Ordovician K-bentonites of eastern North America
Dennis R. Kolata, et. al.(1996)

In the “Garden”

May 8, 2010

Upon returning to the Bluegrass region of Central Kentucky a couple of years ago, the first outcrop that I planned to visit was the type section for the Millersburg mb. of the Lexington Lm.

Generally, though out the Late Ordovician, most of the Laurentian margins were experiencing transgressive sequences, but here, regressive shoal complexes associated with deep-seated tectonics produced the carbonate clastics common to the area.

The Lexington Lm. is a complex assemblage of limestone and shale facies where the changes can be abrupt-both laterally and vertical. The formation is generally a transgressive sequence that grades upwards into the deeper water limestone and shales. However, in the inner-bluegrass region, the Tanglewood and Millersburg members are an exception to the transgressing sea sequences.

The Tanglewood is a thick sequence of coarse-grained calcarenites with local unconformities and tidal influenced structures; many of the beds are cross stratified(The header for the blog is one of those sequences).

The Millersburg is typical of the complex facie relationships of the region. It inter-tongues with the other members of the Lexington above and below, and in some places, it is absent; it isn’t even consistent within its own framework. Drive a few kilometers down the road, or climb/ descend a few meters in the column, and the fauna/lithology changes. The Millersburg is nodular limestone and shale that was deposited above the wave base.

But, I love it! The Millersburg is one of my favorite members of the Lexington Limestone. It is the unit in which I found my first trilobite, and one of my first crinoids. While, it is more known among local invert geeks for the common fossils found in its beds, there are some beds that produce spectacular finds(if you read this blog, you will notice that most of the stuff contained in it is from the Millersburg).

So, back to the start of the post. Driving out Main Street, I noticed that those nefarious engineers had widened the road. It used to be a nice drive in the country; now it is a four lane highway with a median and shoulders to park your vehicle if it decides to quit working. That sent shudders up my spine! Then, as I approached the type section, my heart fell out. It was gone!

The type section gone? How could it be? Perhaps it was ignorance; maybe the reason was economic? Who knows? But, It was gone!

Unfortunately, the destruction of significant geologic treasures is common. I have to assume that the reason is ignorance… how many engineers could know the significance of what they are destroying when they plan their construction projects?

My favorite outcrop was no more. Oh well! One has to move on, and so, I did. About a kilometer down the road, and a 10 or so meters down in the column, there was a tongue of Millersburg sandwiched between some shallower stuff of the Tanglewood mb.

On one of my first visits to the site, I found a nice Pychnocrinus sp., but I didn’t find the bed that it came from. It was located in the float at the base of the outcrop.

width of photo about 10cm

With this clue, my latter visits to the site were spent in the area where I found that little cutie. At first, I wasn’t having a lot of luck locating the bed in which the crinoid was from, but then I climbed a little up in the column, and perched at the edge of a ledge, I found this large pinnate structure.

width of photo about 12cm

Just above the ledge was a bed of clay that pinched out a couple of meters in both directions. That small bed has produced over 40 crinoids in just the face of the bed.

Curiously, a lot of the crinoids appear to be severely weathered… even when pulled fresh from the rock. The rapid changes in lithology-vertically- is thought to be a result of changes in sea level due to tectonic forces related to the Taconic Orogeny. The bed might represent a paraconformity where a small uplift drained the area resulting in the bed’s exposure.

Pychnocrinus (?)

This is one that I found recently. microscope stage for scale

Calyx encrusted by a bryozoan(I’ve never seen this before)
width of photo about 20 cm

Lots of partials(you know the scale by now)

Some are hard to recognize, at first

I have prepped a lot of the crinoids, and some have turned out, nicely. I’ll put some of those up in the future.

Further reading and references:

Contributions To The Geology of Kentucky: Ordovician System

From the Cincinnati Arch to the Illinois Basin: geological field excursions

LITHOSTRATIGRAPHIC FRAMEWORK OF THE TANGLEWOOD BUILDUP, LEXINGTON LIMESTONE (UPPER ORDOVICIAN) OF THE BLUE GRASS REGION, CENTRAL KENTUCKY

Sequence stratigraphy and long-term paleoceanographic change in the Middle and Upper Ordovician of the eastern United States

Extinction, invasion, and sequence stratigraphy: Patterns of faunal change in the Middle and Upper Ordovician of the eastern United States

Unknown Critter/Flora

May 3, 2010

I have encountered this strange structure a few times in my quest to understanding the Ordovician of Kentucky. It is rarely seen, and I always ignored the thing since it didn’t seem relevant to what I was studying. Though recently, I found a few of these, intimately associated, in what might be a lagoonal environment???*

That grabbed my attention, and I submitted photos of this thing to several well known paleo-researchers. Most had no ideal, but Dr. Young clued me in! Probably, algal balls. He suggested a thin section would be determinate, but I still haven’t cut the thing.

When informed of Dr. Young’s opinion, another researcher concurred, but he hadn’t seen any, this large, from the local biota; one other was skeptical.

So, have you seen anything similar?

mag x20

These were found in a mud bed, of limited lateral extent(a few meters), interbedded within the calcarenites of the Tanglewood mb. of the Lexington Limestone.

*perhaps, that is my familiarity with the barrier islands???

Too, why can't I figure out the code of wordpress?

I’m not a ‘puter geek, but I thought that the site was HTML??? Any suggestions?

Crinoid Holdfasts

April 28, 2010

It is a busy week, so a quick post to show a few different crinoid holdfasts from the Ordovician of Central Kentucky.

This first one was recovered from a mud mound in the Tanglewood mb. of the Lexington Limestone in Fayette Co Ky. This outcrop is strange in that the Tanglewood is a calcarenite that was deposited above wave base, and has many local unconformities. As such, the fossils are generally broken and abraded.

At this locality, there is a mud bed that is of limited lateral extent(a few meters) that has produced numerous(about 50) Pychnocrinus sp and Archaeocrinus sp. About the only other fossils found in the bed are bryozoans, an occasional gastropod(Cyclonema varicsosum), and some scolecodonts. I’ll present those in the future.

Perhaps, it was a lagoon, or channel, that protected the community from currents and waves???

Notice the pinnate structure. There might be more to this one.

Close up of above.

Curiously, quite a few of the crinoids from the site are missing the calyx.

In Franklin Co Ky, there is another outcrop that has produced about 100 Reteocrinus sp. The bed containing the crinoids is in the Millersburg mb, and about a meter below the contact with Tanglewood. Since the ossicles are of a different shape than the Reteocrinus ossicles, this is probably from a pinnate form that is uncommon at this locality.

scale in cm

.A few crinoids from the outcrop can be seen HERE.

The last two are the ones that I mentioned in this post. They were recovered from the Clays Ferry Fm. in Franklin Co Ky.

The outcrop in which these were found is known to produce several species of crinoids, but I haven’t spent much time in the field, there. Perhaps, this summer?

A Lovely Critter

April 25, 2010

When driving to my sister’s house in Anderson Co. Ky, the road that I travel traverses the beautiful Kentucky River gorge. The Kentucky River is a meandering stream that was entrenched in its gorge by an uplift in the area during the early Pliocene.

The relatively recent uplift in the area has resulted in an immature drainage of the subsurface that is especially noticeable in periods of heavy rain. In the winter, after a low pressure system moves through the area dropping rain, and if the temps drop below freezing, stunning examples of the immaturity can be seen at many outcrops(more on that in a later post???)

Crossing the gorge on this route, one notices the Austin Nichols distillery; makers of some of the finest Bourbon that money can buy, and a progenitor of some of the greatest times that I have ever had…
Photobucket

… and probably at least one divorce!

The outcrop in the middle right of the photo is the Logana member of the Lexington Limestone. The Logana is a sequence of alternating limestones and shales that is, for the most part, poorly fossiliferous. For that reason, I never gave it much thought. However, at the base of the Logana is the Curdsville mb of the Lexington.

The Curdsville, though sparsely fossiliferous, has been known to produce, exceptionally rare and well preserved, echinoderms and trilobites in shaley partings separating some of the beds.

Finding a place to park for this outcrop is challenging; there used to be a roadside park adjacent to the outcrop in the days before the interstate system, but alas! No more(Too, It is dangerous, as the road is curvy and only about a meter distant). As luck would have it, about a kilometer up the hill is an area where a suitable place to pull over can be found.

So one day, with a little time on my hand, I checked it out.

I found a large boulder that had probably been blasted when the road was cut, and on the boulder was found this Iocrinus sp.
width of photo about 12cm

A few centimeters from the crinoid, this holdfast was found.
width of photo about 10cm

At the time, I only had a hammer and chisel, so I chopped the two pieces from the rock. Hence, the breakage.

Apparently, Iocrinus sp has not been found accompanied with a holdfast, often, and there is some debate as to its type holdfast, ie, was it sessile???

If the holdfast found intimately associated with this critter was its own, well…

addendum: I have worked the outcrop extensively. It is dangerous, and not worth your time. I have “pulled” anything of any substance… which was little, and there are many more productive outcrops in the region. DON’T GO THERE!