I took a short holiday recently and walked the coastal path from Sherringham to Cromer and along the way there is the Sea View beach cafe in West Runton. It is a cafe that serves tea and coffee and ice cream but it also has a fossil museum. Most of the fossils have been found on the coastline of West Runton. So it was a contrast, walking the coastal path in the present day with people pushing dogs in those little buggies and seeing the sea stretch out for miles and climbing the Beeston Bump that is said to have been the base of Black Shuck: the mythical dog depicted in this print from 1577 by Abraham Fleming entitled a strange and terrible wunder and a horrible-shaped thing, and at the cafe in display cases there are deer jaw bones that are double the size we would expect from a deer now, and a cast of the tibia from a Mammuthus trogontherii or steppe mammoth standing 83cm high and fascinating tube-shaped shells, basically the remains of a different land that stood in the same spot.
There is a scientific paper describing the excavations of the West Runton Mammoth that resulted in the tibia cast displayed in the cafe. The paper has photos taken in 1995 that show the sheer size of the bones that were found preserved. Lifting a Mammoth femur or a partial Mammoth skull and tusk of such a weight out of the ground involved coating them with plaster to keep them intact and noting exactly where they were retrieved in the sediment with a theodolite for angle measurement and to a granularity of within ten centimetres. The recording of the bone's positions in the ground was important as there had been previous excavations to coordinate with. In 1990 coastal erosion exposed an enormous pelvic bone at the West Runton cliff site, the paper describes a rapidly-improvised excavation where the pelvis proved both very heavy and much more fragile than it had first appeared, with the unfortunate result that it was recovered in many fragments. However a left astragalus or ankle bone was removed in it's entirety and the pelvis could be pieced together. Between 1991 and 1992 the paper describes the excavations of the mammoth bones surrounding the pelvis stating that about twenty five percent of the Mammoth skeleton was recovered including the mandible and several limb bones, vertebrae and ribs. The positions of these finds in the ground were mapped using a simple line and offset technique. There is a diagram of the near complete Mammoth skeleton from a paper about the evolutionary stage of the West Runton mammoth that shows what was unearthed through the combined efforts of all the excavations up to 1995, from a giant sheet-like shoulder blade down to tiny bones in the tail and the toes. The position of the larger mammoth bones in the ground is shown in outline in this picture of the excavation site, along with the places of excavation of pollen, plant macrofossils, beetles and small vertebrates. The bones are shown in great detail, named and colour coded for tusks and skull and limb bones and the left and right side of the body in figure two of this paper on the taphonomy of the Mammoth bones, taphonomy being the study of how things become fossilized.
The question arises of what sort of setting did this Mammoth live in? Figure one of this paper on the the sediment analysis of the West Runton mammoth excavation site shows that there are signs of a subsidence extending either side of the fossil's ground positions and running parallel with the modern cliff face. Within the subsidence depression there is evidence of a freshwater bed over a chalk base. The same paper on the sediment in the freshwater bed describes through a combination of the chemistry of the silts that turned to sedimentary rock and the accumulation of pollen within them a picture of a fast flowing water with frequent flood events surrounded by grasses and sedges constituting a herb-rich grassland and that later the shelly sandy waters slowed to be stiller and surrounded by birch, pine, elm and alder trees which later gave way to a mixed oak forest. This type of plant life implies that the Freshwater Bed experienced weather between likely glacial cold climates.
The sort of time frames we are looking at placing a setting as aged as the West Runton freshwater bed are those defined by Marine Isotope Stages. The Marine Isotope Stages are a measure of the different forms of oxygen present in the calcium carbonate shells of marine creatures and pollen and plankton in different layers of marine sediment. As described in this video Oxygen can exist in several atomic forms. Here we are concerned with the proportion of Oxygen-16 which has a nucleus composed of eight protons and eight neutrons, compared to the atomically heavier Oxygen-18 which has a nucleus structure of eight protons and ten neutrons. Proportionately high levels of oxygen-18 relative to Oxygen-16 represent cold glacial periods. Working backwards from the present, which is Marine Isotope Stage one in the scale. The stages with even numbers have high levels of oxygen-18 and represent cold glacial periods, while the odd-numbered stages are lower in oxygen-18 and represent largely warmer interglacial intervals. The stages can be divided into sub-stages as shown for example in this study.
Placing the West Runton Freshwater Bed in geological time and relative to other geological settings is a delicate activity. The West Runton mammoth site allowed access many specialists of smaller fossils who extracted specimens from the sediment from defined positions to examine for their evolutionary stages and chemical markers of age. The first table in this paper gives a sense of the range of the species excavated. Some specific studies include those of birds, amphibians and reptiles, molluscs, hyaena, beetles, freshwater shell proteins, fish, deer and horses, voles and mice and volcanic minerals. Here are just two of these studies as examples to get a sense of how such extreme age is processed.
Small mammals such as voles, shrews, mice, moles etc are classed as micromammals. There is a paper that describes how within the main scatter of West Runton mammoth bones samples of micromammals were taken at five centimetre intervals through the complete 1.35 m column of the organic detritus muds. The paper explains how a total of more than 8,000 small mammal remains were recovered of which approximately 1,000 elements (mostly isolated teeth) were identified to species level. For example there are incredible pictures of the jaw and teeth of the shrew Macroneomys brachygnathus from the West Runton site. In total the remains of 16 species of micromammal are described.
One of the species in the paper is a small mammal called Mimomys savini which is a now extinct genus of vole. This species of vole evolved to be larger in size and have noticeably different teeth leading to a gradual loss of ‘mimomyian’ traits as it evolved to the species Arvicola. Scientists have documented these jaw and tooth changes in fine detail, for example figure one of this paper on the dental evolution of voles illustrates the increasingly intricate structure of the first lower molar of the Arvicolinae. The transition from Mimomys to Arvicolinae happened over a relatively short geological time frame and on account of the vole's rapid migration they are found over a wide geography, making them a strong indicator of archaeological site age. As well as West Runton there are other sites in the United Kingdom include Westbury-sub-Mendip, Boxgrove, Waverley Wood in the Midlands and Sidestrand all contain fossils of voles of Mimomys to Arvicola lineage.
With the vole jaw fossils providing a relative comparison for the age of sites, scientists tested other methods to define the age of these settings. For example this paper describes a comparison of protein in two species of freshwater mollusc shells in the West Runton, the Hoxnian site at Clacton-on-Sea, Essex and the Waverley Wood in the Midlands sites. Proteins, the building blocks of living things, are long chains of amino acid residues. The age of fossils and by extension the setting they were extracted from, can be estimated by how the amino acids change over time. The paper describes how Amino acids generally occur in two forms, called stereoisomers or enantiomers, which are mirror images of each other. These stereoisomers were originally named by the direction in which they rotate plane-polarised light: laevo-rotatory (l) and dextro-rotatory (d).. Here is an example of one of the amino acids, Serine, studied in the freshwater shells in both it's l and d form Serine L-Serine (left) and D-serine (right). When an organism such as a freshwater mollusc is alive the amino acid residues in proteins are of the l-form. When the organism dies or when there is no more tissue-turnover the paper describes how the l-form is thermodynamically unstable and then spontaneously the l-form slowly turns into a mirror image d-forms until an equilibrium of d- and l-amino acids is reached. This process is called racemization and it occurs at particular rates over long time frames. Racemization is influenced by temperature and ph and so it is an estimate of extreme age.
The paper measured the racemization of five different amino acids from different locations on the shells of two species of mollusc: Valvata piscinalis and Bithynia tentaculata which were present in all three sites. The results for each of the three sites are presented in a table that compares the extent of racemization of five amino acids. This table along with figure one leads to the authors of the paper to state that the extent of protein decomposition in the West Runton opercula is significantly higher than those from both Clacton and Waverley Wood. This is fitting with the paper that describes how the fossils of the water vole Mimomys savini was found in the West Runton site while it's evolutionary descendant Arvicola was present at Waverley Wood. The authors continue that at the 95% confidence level, 5 and 7 out of the 12 protein decomposition indicators from the Valvata and Bithynia shells respectively show that the WRFB is significantly older than Clacton, whilst all 12 of the protein decomposition indicators from the Bithynia opercula support this. This paper concludes that it was too early, on the basis of the amino acid data alone, to attribute the West Runton Freshwater Bed to a particular stage in the marine oxygen isotope record, although a pre-MIS 13 age is indicated, which represents a time frame that started 524 thousand years ago.
There we have it, a little something of how scientific papers describe a setting like the West Runton Freshwater Bed and a phenomena like a buried mammoth that would have been twice the size of a elephant today, with the details of lifting bones of such an enormous size out of the ground, coating and protecting them and noting exactly where they were placed, the tiny jaws and teeth and evolution of a water vole, the pollen and spores that would have floated in the air and the plants that created them and the weather that the plants would imply, the chemistry of long term ageing in oxygen isotope ratios in marine shells that provide a climate framework and the minute changes in amino acids that occur once living creatures are preserved in sediment. I like the intricate connection of one detail of this setting relating to another to give a picture of time and place and that it all came from a holiday walk along a cliff to a cafe. I also like how similar the scientific method is to writing fiction which is about everything doing its work of explaining something else.