It started in the year 2000 when accurate positioning using a GPS receiver became available to the general public. There are now more than 3 million geocaches worldwide, published on the geocaching.com website, and probably three times as many geocachers involved in searching for ones local to them.  These are people who are regularly out and about in town and country, but many have little knowledge of geology and geomorphology. That is where Earthcaching comes in.

Earthcaches are a subgroup of geocaches, where there is no box to be found at the location, but instead there are aspects of geology to explore.  The person setting the cache writes a brief description of the geology, together with a few questions that the finder is required to answer at the location. The idea is that these should combine to provide a short earth science lesson for an adult with no previous knowledge of geology. Photographs and diagrams can be included in the description, but diagrams and text need to be kept simple, remembering that many cachers will be reading the material on the screen of their smartphone or GPS, not on a computer screen. Finders subsequently contact the cache owner with their answers and can then log the cache as a ‘find’ on the geocaching website. Many earthcaches are at conventional geological outcrops, others relate to building stones, and some look at geomorphological features such as modern dunes or glacial moraines.

All geocaches are graded according to their difficulty and terrain, on a 9-point scale running in half units, from 1 to 5. In general, earthcaches would have a low difficulty rating since the questions should be relatively straightforward to answer. The terrain rating will depend on how tricky it is to get to the cache site. One near the summit of a Lakeland fell might have a terrain rating of 4 or 4.5, while one looking at polished stones in a shopping centre, accessible to a cacher who uses a wheelchair or with a child in a buggy, would have a terrain rating of 1.

Before an earthcache can be published on the geocaching website, it is submitted to be checked by a reviewer with a geological background, who satisfies themselves that the geological information provided is accurate and the questions appropriate. They also must be confident that relevant permissions have been obtained if the cache is on private land, or land owned by organisations such as the National Trust. For this, the government sponsored MAGIC map (Multi Agency Geographic Information for the Countryside) is invaluable and most landowners are happy to give permission.

Monolith and Shadow - the site of an earthcache outside University College Hospital, Euston Road, London, where cachers answer questions about the types of rock present in this fascinating sculpture.

The number of visitors to an earthcache will, of course, depend on its location. One of ours in central London is currently getting about 20 visits a month, while another, at one of Cumbria GeoConservation’s Local Geological sites, on the west coast near St Bees, has had about 20 visits in the last year. But that’s 20 people, or groups of people, who have now had an introduction to features in Triassic sandstones who might previously have never given these lovely rocks a second glance, as they walked along the coastal path.

List of current Earthcache sites at/near Cumbrian LGS sites.

Earthcaches are a great way to encourage non-geologists to learn a bit more about our fascinating subject.  There are already earthcaches at Land’s End and John O’Groats but choose somewhere between and you can set your own!

Audrey Brown (Cumbria GeoConservation)

Earthcache blog

Exploring clints and grikes on the Gait Barrows NNR, Arnside and Silverdale AONB, for an earthcache concerning the development of limestone pavements.