English Tethys Eocene tiny marine fossil (not identified)
No idea what this tiny fossilised creature is. I intend taking photos of it at higher resolution to add to this post. It’s in a pebble/cobble of Mixon Alveolina Limestone dredged from the Owers Bank in the English Channel several miles off Littlehampton, which is thought to date from the Bartonian age of the Eocene epoch, deposited in the north western extremity of the Tethys Sea about 40 million years ago.
(Unfortunately I’ve “mislaid” this micro-fossil amongst the dozens of pebbles and cobbles of this English Tertiary “limestone” that I’ve collected. So, until I locate it again I won’t be posting more pictures of it. As to identifying it, I’ve been looking at bryozoa and closely related families of species which I know next to nothing about. If anyone can give a pointer to identify this micro-fossil then please use the “Contact” page to give me information about it).
(NB. I’ve mislaid this specimen. I’ll post more on it when I find it).
Odd Eocene marine microfossil in Mixon Alveolina Rock pebble. Image width 2.4 mm (Taken with DSLR)
Two photos of an odd microfossil in a pebble of Mixon Alveolina Rock (Eocene, likely Bartonian) probably originating from reefs offshore of Selsey Bill, West Sussex. The photos are taken with a DSLR fitted with a microscope objective lens, and lit with a bright white LED torch at an oblique angle of about 35 degrees. The pebble has been polished with various abrasives. Previously on this website I’ve referred to this material as limestone. The material is variable, and the exact original in situ sources uncertain. If it all (or most of it) originates from a contiguous bed, then that strata varies in its composition from high calcium to high quartz sand content. However, some samples appear to have perhaps undergone a process of “silcretisation” (or maybe “calcitisation”?) so could possibly be called a silcrete (or maybe a “calcrete”?), andsome evidence of either can possibly be seen in these photos of this specimen. The material is generally known, amongst other names, as Mixon Rock, although I’m now choosing to call it Mixon Alveolina Rock to distinguish it from a limestone rock outcrop in Derbyshire called Mixon. Limestone, sandstone, or silcrete: I currently remain unsure of the the most accurate classification Concerning the odd microfossil shown in the photos, I’ve not yet come across other like examples in the other samples of this rock I’ve looked at.
Odd Eocene microfossil in Mixon Alveolina Rock (Taken with DSLR)
…………………………………………………………………… A further two pictures (below) of the same microfossil taken with a hand-held USB microscope, one with polarizer on, the other off, both with dimensions:
Eocene marine microfossil in Mixon Alveolina Rock USB microscope with polarizer on
Eocene marine microfossil in Mixon Alveolina Rock taken with USB microscope polarizer off
The picture below of a polished face of a Mixon Alveolina Limestone pebble has been achieved by stitching together about 60 photomicrographs at X20 magnification taken with a USB microscope. The file size is large to allow zooming in (three successive clicks on the image eventually brings up a highly zoomed in high resolution image). Some digital enhancement has also been used, and other pictures of this pebble on this website give a truer, more natural colour rendition.
The alveolines are taken to be Alveolina fusiformis (Sowerby), and their wide morphological variation has previously been noted by C.G. Adams in Alveolina from the Eocene of England (1962). Adams left open in that publication the possibility that Alveolina elongata (d’Orbigny) was actually a variant of fusiformis.
Mixon Alveolina Limestone pebble max dimension 55mm (multiple stitches and considerable digital adjustments)
An unidentified foram with alveolina in Mixon Limestone
This blog post is about an examination of a foramaniferal rich Mixon (Alveolina) Limestone pebble originally dredged from the English Channel about 7 miles off the West Sussex coast.
Mixon Limestone is thought to date to the Eocene epoch, Bartonian age (37.2 – 40.4 million years ago), and to relate to a Tethys Sea shallow benthic zone (SBZ 17) at its far north western edge in the Hampshire Basin of England.
The examination is mainly done with a USB micropscope offering magnifications of X20 and X400 under reflected light.
Grinding and polishing is done with diamond sharpening stones of grit sizes 200, 300, 400, 600. Further polishing is sometimes done using up to 2400 grit emery paper.
Some digital enhancement is sometimes done in Photoshop, usually restricted to cropping and adjusting brightness/contrast with the “Levels” tool.
Also, sometimes a stitching programme is used to combine multiple photos together.
Sometimes a scanner or digital camera are used for the pictures.
Foraminiferal rich limestone pebble.
A gallery of photomicrographs of the forams in this pebble can be found in the link on the right to the page titled “Examining a Mixon Alveolina Limestone Pebble”. Some scans and photos are also included.
Same Alveolina , as enlargement below, with dimension annotated.. Polished specimen.
Oblique sub-equatorial polished section of Alveolina in Mixon Limestone from off Sussex coast, Owers Bank,
English Channel. Probably Bartonian of the Western Tethys. Maximum dimension of foram is 2.9MM.
Foram, maybe Nummilite sp, (size dia 1.2 mm) in Eocene, Alveolina (Mixon) Limestone, probably Bartonian (about 37.2 to 40.4 million years ago) Corresponds to shallow benthic zone (SBZ) 17, and probably just above (later than) the “Calcaire grossier” of the Paris Basin, a basin of a transgressive phase of the Western Tethys. Dredged from off Sussex coast, England, in the area of the Owers Bank..