A few months ago I wrote an article for Stockport & District Heritage Magazine. Being in a curatorial role and currently part of Stockport’s collection team I took this opportunity to explore one of my favourite pieces in the collection with a history in this town; the Rapping Hand. This has also been a past Find it Friday object, that you can read about HERE.
Now, in the next few weeks I will be writing another article for the magazine so I have been exploring my favourite part of the collection here at the curatorial services for inspiration; Geology (of course!).
We have quite a large geology collection despite having no current sites in which we exhibit natural sciences, after the unfortunate closure of Vernon Park Museum. But alongside the same reasons museums hold natural history, ornithology and entomology collections mentioned in earlier posts (orni HERE, ento HERE, nat. hist HERE and HERE), the collection is essential for scientific exploration, development and understanding.
In our geology collection we hold a wide variety of rocks, minerals and fossils, including some wonderful specimens from the Great Wall of China, the Great Pyramid of Giza in Egypt and a piece of basalt in the characteristic column shape from the Giants Causeway in Northern Ireland. Unfortunately, these pieces with somewhat high-profile origins have no information but this on their records on MODES. This means there is no way to find out how or why they came to be part of our collection. Of course, we are located nowhere near any of these three sites so the reasoning can not be one of relevance. However, perhaps they were collected by someone with local relevance. A lot of the mineral collection we hold was donated by a Miss Caroline Birley.
Birley (1851 – 1907) was a local Geologist, (and possibly a contender for my favourite scientist of all time, fighting it out with the equally amazing Mary Anning!) born in Manchester, she dedicated her whole 55 years to her science never once allowing her passion to weaken or stray. Yet even so she is a relatively unknown name; read more about which of her collection pieces we hold, and about Caroline Birley HERE.
Birley’s natural compulsion to curate her collection means that when she sadly died and her collection distributed between various museums in the local area the pieces were accompanied by all their relevent and useful information; dates, locations, etc.
We can say this about quite a large chunk of the fossil collection too. The original information is with a lot of the samples we have as well as the identity of collectors, donors etc, information that essential for effective collections management.
Unfortunately, we can not say the same about this fossil that was found in a bag of soil that the donor had ordered in preparation for some renovations that were happening in their garden… that’s all we know!
This belongs to a small collection within the larger geology collection that I am often drawn to; the Ammonites.
The invertebrate Ammonites, of the class Cephalopoda are recognisable by their usual (but not always) planispiral coiled shape. They are extinct now, but they are still considered to be one of the most important of marine creatures in the fossil record. Cephalopods, but in particular Ammonites, had a rapid and varied evolution, this makes them some of the best zone (index) fossils. This means that as various types of ammonites only existed at specific points throughout the geological record the presence of one in a rock can then date that rock.
Ammonites were marine creatures, they swam in the seas while the Dinosaurs dominated the land and in fact, were around for over 330 million years, making them more successful than the dinosaurs at 130 million years! (Yet both succumbing to the same mass extinction, 66 million years ago.)
Cephalopods were not unlike the living Nautilus and existed in the same way. They had suckered tentacles which are not fossilised as they were soft material. They moved quickly through the waters with a type of propulsion, pushing them through the water and allowing them to be active predators.
Ammonites have coiled shells divided in to a series of chambers by septa. The animal inside however only occupied the largest chamber, next to the opening. As it grew the animal moved forward creating a new chamber and so extending the coil behind the first. The then empty chambers were filled with water and gas which caused the propulsion of movement. Although the various types had shells that differed in shape, orientation, coil thickness, degree of coil etc, here we only have samples very similar in shape, but vastly different in size. (The size can be an indication of various things; age, species or gender.)
We only have two that have been scientifically identified:
Promicroceras, which is our smallest Ammonite. It shows strong ribs around its coiled shell and can be dated quite specifically to the middle of the lower Jurassic. This specimen was found in the Lower Lias rock of Whitby.
And Ammoites Communis. This one dates to the upper Jurassic and was found, again in the Lias rock, but in Lincoln.
We have detailed information regarding the others but they are only identified as “Ammonites”. This is a shame, and perhaps something I will make an active effort to change. Even though above I said they all appear quite similar, if you look closely you can begin to see the individual differences and features and it is a real pity not to have a complete understanding of these beautiful, significant fossils.