The UBSS expedition to northern Thailand during December and early January 2000/2001 investigated a previously unexplored area of karst near the northern border with Myanmar. A total of 2.5 km of cave passage was mapped in four adjacent areas and a large number of karst sites were investigated. The two largest caves were 718 m and 758 m in length. However, high levels of carbon dioxide in many of the caves proved a major hindrance to exploration. A description of the finds, coupled with a brief interpretation of the geology and geomorphology of the area is given below.

The current surface hydrology associated with St. Cuthbert’s Swallet was studied between 1994 and 1997 by frequently sampling at 3 sites. The study period included spells of heavy rainfall in November 1994 and spring 1995 and a drought of historic proportions in 1995 when the Mineries Pool Outflow stream (the largest stream entering the cave) and a nearby spring stopped flowing. When flow of the Pool Outflow stream resumed, a huge surge of calcium sulphate appeared in its water. Most hydrochemical properties showed very low variability at Fair Lady Well. Periods of intensive sampling enabled the response of hydrochemical features to stream size to be investigated. Total, calcium and alkaline hardness varied inversely with stream size at the Pool outflow stream and at the main stream sink. Aggressiveness varied with stream size only at the Main Stream Sink. The mean concentration of nitrate in St. Cuthbert’s Stream was below 4 × 10-5 M. Concentrations of potassium and nitrate showed seasonal variations except at Fair Lady Well. After the 1995 drought, the long delay before the Fair Lady Well flow restarted implies that the aquifer has an unknown lower point of discharge which had continued to flow after the well stopped flowing.

At every site where water flows from a surface stream sink to an inlet in the cave, there are changes in calcium, magnesium and bicarbonate concentrations, in spite of the fact that in many cases, these distances are short. The changes are caused by limestone dissolving in the stream in the space between swallet and the open cave, and not by admixture with water percolating from a different source. When the size of a surface stream rises, concentrations of many solutes in the stream, including calcium and bicarbonate, fall. However, results show that at every near-surface inlet for which sufficient data is available, the rate of limestone solution increases when stream sizes rises. Once the stream is within the open cave, stream characteristics are remarkably stable and, in sampling trips in normal conditions, they only change when mixed with water from a different source. The present results demonstrate that the quantity of limestone passing into solution increases very considerably as a result of an increase of stream size. Although the total volume of the streams entering the cave is the same as it was in the past, after the largest stream entering the cave changed its route the hydrochemical characteristics of the Main Stream downstream of Plantation Junction have changed. The change is not limited to an increase in the hardness of the stream. Although the number of data points is small, it is clear that the response of the total hardness to stream size has undergone a major change. Regression equations describing temperature changes between the sinks and the inlets were statistically significant in the earlier period of study when more sensitive thermometers were used.

Three seasons of fieldwork at Middle Down Drove, Cheddar in the Mendip Hills, Somerset (centred on ST485 526) are reported on. The work involved the investigation of a previously known flint scatter, further fieldwalking and the partial excavation of a round barrow. Geophysical surveys were also undertaken, revealing a possible prehistoric field system that incorporated the round barrow. Although fairly limited in scope, the project uncovered new information about prehistoric activity dating from the Mesolithic to the Bronze Age in this area.

During the Second World War, phosphate and flourspar deposits close to Doolin, Co. Clare, were investigated by the Irish Government’s mining company, Mianrai Teoranta and underground workings developed to exploit them. The flourspar deposit proved unproductive, but the phosphate deposit, which had previously been privately worked by an opencast quarry, was highly productive and was worked until 1947. The earlier opencast workings had stripped the shale covering from the bed of the Aille River, allowing it to sink into the subjacent Doolin Cave System. The existence of this open cave beneath a surface river flowing on limestone has previously been explained by reference to the heterogeneous nature of karst aquifers but can now be attributed to human activity.