These new finds follow the discovery of a presumed Mesolithic engraving at Aveline's Hole in Burrington Combe, Somerset by UBSS in February 2005.
The team, led by Graham Mullan and Linda Wilson, carried out investigations in a number of the Cheddar Gorge caves. In a cave known as Long Hole, they found a series of abstract engravings which they have provisionally ascribed to the Mesolithic (or Middle Stone Age) period which began more than 10,000 years ago.
Long Hole is located immediately above Gough's Cave, the major show cave in the Gorge. The cave consists of an elliptical tube leading 250m back into the hillside. The engravings are located on the west wall of a small chamber, about 70m from the entrance.
Three separate engravings of rectilinear abstract designs were found in this chamber. The designs appear to have been cut with stone tools and show a degree of patination characteristic of considerable age.
Graham Mullan said: "On stylistic grounds, we have attributed these engravings to the Mesolithic, rather than the Palaeolithic era because, as in the case of the Aveline's Hole panel, such abstract designs are more characteristic of that period. Although abstract designs are found in the Palaeolithic, they are almost always in conjunction with representational art.
"Unlike Aveline's Hole, which was sealed from the Early Mesolithic until 1797 ruling out any possibility that the engravings found there were Neolithic or Bronze Age, Long Hole has always been open and subject to visits throughout time. It is known to have been used in Roman times and contains graffiti dating as far back as 1668.
"However, although the immediate archaeological context for these engravings is not secure, both Palaeolithic and Mesolithic archaeology can be found in abundance in the surrounding caves notably, Gough's Cave, and it is not uncommon in France and Spain to find cave art in situations removed from the archaeology."
Bob Smart of Cheddar Caves said: "We are delighted by this new discovery which is an excellent example of the importance Cheddar Caves held for our ancestors. Congratulations to the team for a very exciting and significant discovery."
The Spelaeological Society's research into the engravings is being carried out in conjunction with the British Museum's Department of Prehistory and Europe.
Jill Cook, Deputy Keeper in the Department said: "Just when we thought there was not much more to find out about Long Hole, an excellent new discovery has been made which pulls it right back into research. The new engravings are clearly ancient and comparable to early post glacial pattern panels found elsewhere in Europe. Their discovery will help to breathe new life into research on this period."