Somerset ammonites, with one two big surprises

[Aurelius]

I went on a jaunt to Somerset yesterday, for a hunt around in the Beacon Limestone. These rocks are Toarcian in age (~174-182m years old). I found many of the usual ammonites, but also a couple of big surprises.

 

First, the usual finds.

 

These harpoceras ammonites are often very well preserved, and usually display their sutures (you'd be lucky to find one with much shell on it). It has iron deposits on it, but a bit of time in the blasting cabinet and it'll be a uniform grey (which is nicer than it sounds).

 

 

Here's another harpoceras, with a small oyster attached. This will take a bit of prep to remove the plug. Often the centres aren't complete.

 

 

These large examples of dactyloceras are quite common in one layer, but the larger ones almost never seem to be complete to the very centre.

 

 

I sometimes pick up broken examples, because they often break along the suture lines. This one might look quite decent when I pen it and blast away the orange deposits.

 

 

These jumbled up pieces of matrix are fairly common, and contain lots of ammonites. I've also very occasionally found shark fin spine fragments in them, the only vertebrate remains I have ever found in these rocks.

 

 

When I spotted this, I wondered if it might be a large teuthid phragmocone, which you do (rarely) find, but it isn't. I wonder if it might be a lobster burrow?

 

 

A small nautilus which has had a bit of a knock.

 

 

[Aurelius]

Here's the surprise part. I saw a large rock poking out of the ground, with what appeared to be the keel of an ammonite. I knew it couldn't be, because it was too big, but I turned it over anyway, out of curiosity. It was this:

 

 

This is one serious ammonite! In addition, it's not an ammonite that I should have found in Toarcian rocks. I'm not an expert, but I thought it was probably coroniceras, an ammonite commonly found at Lyme Regis. However, coroniceras is a Sinemurian ammonite, that lived 8+ million years before these rocks were deposited. You don't find ammonites this big in these rocks (or at least, I never have!).

 

By this stage, I imagined that I must be hallucinating, so imagine my shock when I turned over a rock a few feet away, and found this.

 

 

So that's two of them, in the middle of nowhere, in an area packed with toarcian (and to a much lesser extent, Pliensbachian) fossils.

 

Both of them are very worn, although there's evidence of shell material retreating back into the rock, so I can probably prep from the other side, and am hopeful for a good result.

These don't appear to be from Lyme (wrong type of rock). In fact, in terms of appearance and preservation, these do look rather like the local rock, once it's been buried for a decade or three. The worn look and patchy shell preservation remind me of the reworked fossils you often find in this formation (it's common to find earlier fossils in later layers, which have been heavily worn and then re-deposited). Could these be reworked from an earlier layer, or are they more likely fossils which have been dumped here for reasons unknown?

 

Close-up of the worn shell:

 

 

This is the reverse of one of the blocks, to show the type of rock:

 

 

Any thoughts would be very welcome! 

 

 

[Heteromorph]

Beautiful peices! What kind of lighting did you use for the pictures? Sunlight or good artificial light? 

[fossilized6s]

Nice finds! That is a biggin'! Congratulations. 

[KimTexan]

All of them look nice, but even the last 2 look better preserved than almost anything found around here in North Texas.

Nice finds. Do you keep all that you find?

[Miocene_Mason]

I’ve got little to no knowledge on these areas, but they are some nice Ammos

maybe somone like @JohnBrewer would I know more.

[Nimravis]

Some impressive finds- congrats.

[Aurelius]

Thank you for the kind comments. 

 

2 hours ago, Heteromorph said:

Beautiful peices! What kind of lighting did you use for the pictures? Sunlight or good artificial light? 

 

I used the last dregs of indirect sunlight before the sun disappeared over the horizon! I had to use quite high ISO on some.

 

1 hour ago, KimTexan said:

All of them look nice, but even the last 2 look better preserved than almost anything found around here in North Texas.

Nice finds. Do you keep all that you find?

 

I do keep everything at present, but I will be selling some soon, and also possibly giving some away.

 

Just in case anybody's interested, here are some prepped examples, to show how they come up.

 

 

 

 

 

 

 

[JohnBrewer]

Nice finds! Didn’t know you resided in the UK.

[sixgill pete]

Great finds. I love ammonites, they are just really rare here in North Carolina.

[Monica]

Beautiful prep job!!!  Wow, wow, WOW!!! 

 

I like this one in particular - the suture pattern is so clear!!! 

 

3 hours ago, Aurelius said:

 

 

[Ludwigia]

@Aurelius First of all, nice finds! Now a question. Is your exposure an outcrop or are you finding these fossils on a field? You mentioned that the out of place rocks were poking out of the ground. My first thought would be that someone deposited these ammonites there a long time ago, but why? They appear to be in quite good condition. Is it possible that there is a hiatus in the area which omits the entire Pliensbachian?

[Aurelius]

Just now, Ludwigia said:

@Aurelius First of all, nice finds! Now a question. Is your exposure an outcrop or are you finding these fossils on a field? You mentioned that the out of place rocks were poking out of the ground. My first thought would be that someone deposited these ammonites there a long time ago, but why? They appear to be in quite good condition. Is it possible that there is an anomaly in the area which omits the entire Pliensbachian?

 

Thank you! This location where I found them is soldly toarcian, with upper pliensbachian beneath. They were found in about two feet of mud which covered a vertical section through the formation. They were not in-situ.  But they were found about a foot away from a large cutting through about ten metres of the formation, so it is conceivable that they were disturbed while the cutting was made and deposited there accidentally, as were plenty of other fossils.

 

On the other hand, I can't escape the probability that they were placed there. If I had found just one, I would be more inclined to believe it might be a freak reworking of a sinermurian fossil, but two next to each other seems like far too much of a coincidence, given that I have never found any others. But why someone would ever dump these fossils there - and where they may have originated from - is a mystery to me.

 

I've always wanted to find a nice big coroniceras, and to find two here (if that's what they are) is baffling. I'm hoping they'll prep nicely from the back.

[Ludwigia]

6 hours ago, Aurelius said:

 

   But they were found about a foot away from a large cutting through about ten metres of the formation, so it is conceivable that they were disturbed while the cutting was made and deposited there accidentally, as were plenty of other fossils.

 

"Plenty of other fossils" from which stage? Sinemurian or Toarcian? Is this location in a quarry?

 

[Aurelius]

6 hours ago, Ludwigia said:

"Plenty of other fossils" from which stage? Sinemurian or Toarcian? Is this location in a quarry?

 

All Toarcian, or upper pliensbachian. The location is a farm - the toarcian deposits are just below the surface over an area of many miles, so road cuttings, building work or ploughing will always expose fossils.

[Everhardus]

Lovely ammonites, hope to visit Somerset one day.....

[Ludwigia]

9 hours ago, Aurelius said:

All Toarcian, or upper pliensbachian. The location is a farm - the toarcian deposits are just below the surface over an area of many miles, so road cuttings, building work or ploughing will always expose fossils.

In that case I'd assume that someone dumped them there a long time ago.

[RJB]

Very interesting thread.  looking forward to seeing how that second big turns out after prepping?

 

RB

[old bones]

What Monica said !

[oldtimer]

Very nice finds.  I am interested in how that big one preps out.  Wish I could find large ammonites like that in my area.

Thanks for sharing. 

[MeargleSchmeargl]

On 12/28/2017 at 3:40 PM, Aurelius said:

Thank you for the kind comments. 

 

 

I used the last dregs of indirect sunlight before the sun disappeared over the horizon! I had to use quite high ISO on some.

 

 

I do keep everything at present, but I will be selling some soon, and also possibly giving some away.

 

Just in case anybody's interested, here are some prepped examples, to show how they come up.

 

 

 

 

 

 

 

Drool bucket material, folks!

[Aurelius]

A couple of days ago, I found this on the same site. This certainly originates there, probably from the pliensbachian marlstone (Spinatum zone), but I can't work out the species. I've found these occasionally in field brash, always just the body chambers. 

 

I don't know if this is pertinent in any way, probably not, but I would be interested to know what this is, if anybody knows.

 

Many thanks.