Archaeology and caves
Archaeology…
can be a difficult subject to get your head around - stratigraphy, relative dating, absolute dating, typology, burial environments, weathering, magnetometry - and these are just a few of the unfamiliar words the uninitiated might encounter. Yet these are nothing compared with the many aspects of archaeological theory and changing archaeological paradigms which exist within the broader science of archaeology. But don’t be put off by this - the basics of archaeology are a lot easier to learn about and there are some good books on the market (see publications page) which explain the accepted methods of working in the field, whether making a survey of features in the landscape or carrying out excavation work.
Most archaeologists work on “terrestrial” sites in towns or fields. Sometimes they get muddy and rained on, but generally speaking things aren't so bad; they don't bang their heads on the roof every time they stand up and they are usually not far from a pub! Other archaeologists work up mountains or under the sea, where the technical and safety aspects of operation are more demanding. Some of us work in caves, which present an entirely new set of risks and working challenges. Take stratigraphy, for example: as in geology, archaeological layers or sediments are deposited in chronological order but can be subjected to many forms of disturbance. In geology, rock layers can sink, lift, twist, or get worn down by erosion so that whole chapters of evidence are destroyed. The remaining earlier layers may then be topped off with new deposits millions of years later, setting difficult questions for the Earth scientist who aims to understand how the landforms developed over time.
Geological unconformity at Foredale Quarry, Helwith Bridge. Yorkshire Dales
Such “unconformities” also occur in archaeology - deposits of material can be truncated by later activity, or they can be dug up (not only by archaeologists) and redeposited in a different order. They can move from one place to another, sometimes through human or animal activity, sometimes transported by the natural movement of material - here water can be a major element in displacing cave sediments and any archaeology they may contain. Putting it simply, cave sediments are generally not always the easiest of deposits to comprehend, since the correct conditions for the preservation of chronologically deposited layers are often absent. If your archaeology has been turned over and over for centuries by the digging of badgers (the “washing machine effect”) you will have a problem in piecing it together to tell a coherent story! If all this wasn’t enough, the challenges of operating in cave environments, with all the attendant health and safety risks, can be very demanding.
As a caver, what can you look out for?
Perhaps the first thing which may indicate the archaeological potential of a cave site is the type of cave in question. Ask some basic questions - is the cave entrance in a scar or cliff which has probably been known for centuries or throughout human presence in the locality? If so, you will obviously not be the first to have visited it or used it. Has the cave entrance have been subjected to erosion by glacial action or later collapse - cave entrances can recede so archaeological material may be deposited some way in front of the present entrance. How accessible is the cave? Would the entrance have been easily visible and would it have been easy to enter in the past? Some caves were used for ritual and burial purposes and prehistoric people sometimes made great efforts to access more “secret”, inaccessible places. Could the cave be classed as a shaft? Shafts are often filled with modern farm refuse but may also be receptacles for significant earlier archaeology. Things, people or animals can fall down, be thrown down, or be placed down shafts; due to the vertical nature of shafts, material can be spread over different levels to considerable depths.
Look at the sediments in caves - have they been cut through by streams or digging; are there intact sediments near the cave walls; do they have a lot of bone in them or is bone or other material present on the floor? Is there stalagmite flooring above, or at different levels in the sediments; are there bones or other material above, below or within stalagmitic flowstone or calcite? Such evidence of how the cave sediments have formed is key to understanding how any archaeological material came to be locked up in it.
Animal bones are very common in caves and are sometimes found a long way into a system - animals may have fallen down long since in-filled shake holes, so their remains are situated far from any present day entrances. Large animal bones are not the end of the story however, as some sediments may contain pollen, phytoliths and many thousands of the bones of microfauna, such as amphibians, shrews, voles, beetles and the like. These are very important deposits as they can be processed and analysed to provide information about the environment in which those animals lived. Climate, vegetation types, tree cover and average temperatures can all be indicated by scientific analysis of these sediments. Sometimes, bones or other evidence, as well as rocks and other sediments, are transported by water flows a long way from their point of origin within a cave.
Digging is destruction!!
All archaeologists realise that excavation is destruction - when digging, you destroy the evidence which has lain there for centuries until you came along and disturbed it - once it’s gone it’s gone!! For this reason, archaeological excavation should only be carried out in conjunction with a comprehensive recording system - findings are measured, drawn, described, photographed, sampled, tested and often number crunched to the n’th degree, using statistical methods of analysis. Conclusions are drawn and reports written and published. All of this can be expensive and very time consuming, so if the resources to do all these things are not available, one had better not start in the first place! We have the choice of balancing “preservation by record” with “preservation in situ” - the latter meaning you leave it where it is until someone does have the resources and a legitimate reason to tackle it.
These days, cave excavations tend to be on a much smaller scale than was the case in the late 19th Century to mid 20th Century, mainly due to the high expense in money, time and manpower when organising, excavating, processing, paying for dating and doing post-processing analysis. On the positive side, such partial interventions into existing deposits mean that much of the evidence will remain in place for future investigators, whose armoury of scientific methods will surely have improved upon those we have today.
How can you help when exploring or digging in caves?
Any digging, either for archaeological reasons or in the extension of a cave system, has the effect of removing deposits which have amassed over long periods of time. The secret of how these deposits came to be there may be revealed in the stratigraphy, or layering, of the individual components of the whole - clay, silt, sand, gravels, boulders, flowstone and so on. Therefore, an attempt should be made to record, in both the horizontal and vertical planes, the nature, thickness and depth of these individual layers before they are removed in their entirety. If only partial removal will suffice for the job in hand to continue, then this is preferable to complete removal, as others who come after you may benefit from having intact evidence to inspect for themselves.
The overriding principle is that information must be recorded before it is lost, and this principle is equally significant whether one is considering cave formation processes, palaeontology or archaeology. Artefacts, bones or microscopic environmental evidence are generally found within a matrix of other materials, and so the recording of those materials is of vital importance.