Sustainable Mapping of Caves

 Phillip Häuselmann and the UISIC have prepared a paper presenting the whys and hows of good surveying practice. It was published in Issue 10/11 of Speleology, cover dated August/December 2007.

 

The article sets out to present some guidelines for how to perform a survey that is complete, of high quality and sufficiently well documented that it can easily be supplemented with new finds without having to be done again in its entirety. First, the authors set out the basics of good surveying technique: using good quality, properly calibrated, instruments; accounting for sources of systematic error; using stations that can be refound and at which the passage dimensions are measured; and drawing a detailed and accurate sketch. The subject of marking stations is controversial as some object to marking the cave in any way. The principal author's preference is for marking and labelling points at critical junctions discretely such that they can be found only if actively searched for. 

To be complete, the survey should include plan, extended elevation and cross sections, and should be accompanied by a written description. All elements should be provided for all caves, even if it isn't immediately obvious that the particular view offers any useful insight into the nature of the cave. The plan view is often the most useful for navigating round a cave, showing as it does the width and orientation of the passages and their relationships to each other and other caves. This latter point is also true for predominantly vertical caves, so plans should always be drawn as even with limited lateral extent any preferred orientation of cave development and the relationship to other caves in the area can become apparent. 

The extended elevation and cross sections give details of the shape and vertical extent of the passage that is not obtainable from the plan view. The authors argue that extended elevations are preferable to projected elevations because, for projected elevations, information is lost for passages orientated perpendicular to the plane of the elevation. Furthermore a projected elevation can be derived from an extended elevation whilst the reverse is not true. Projections have the advantage of allowing the relationship between cave passages and surface features to be easily seen. Elevations and cross sections offer much more information about the genesis of the cave than can be obtained from the plan: vadose and phreatic passages can be easily distinguished, and different levels of cave development identified. Hence elevations and cross sections provide useful information even for predominantly horizontal caves. 

The written description is intended to cover observations made by the surveyors that cannot easily be ascertained from the map itself – for example geological and biological notes and hazard assessments. 

The advantage of a high quality drawing over a rough sketch is obvious when detailed scientific studies are to be conducted, but are also more useful for for sport cavers. For example, detailed sediment maps can be a useful aid to identifying suitable sites for searching for continuations of known passages. In the cave it is important to sketch to an appropriate level of detail, which will be determined by the scale the final survey will be drawn to if known. If the final scale is not known, it is better to err on the side of recording too much detail as the level of detail can be reduced at a later stage while absent detail cannot be created later. 

The authors make the case for publishing completed surveys, or at least archiving them with a trustworthy body on condition of secrecy should this be considered necessary. If you own the only copy of a survey and it becomes lost or destroyed, all the work that went into creating it will have to be duplicated. The authors also advise that all the original data and survey notes should be archived. Finally, it is advised that paper copies should be made for long term storage rather than relying on digital media that may be unreadable in the relatively near future. 

Overall, this article offers a concise description and justification of good cave surveying practices.