The Schlumberger Resistivity Depth Probe consists of the box of electronics and four reels of wire. Also required are two 100m measuring tapes. All this had to be lugged up to the surveying site by hand as the farmer keeps the gate at the foot of the track locked.

It was an excellent day for field work, for though the temperature was probably near zero, the sky was absolutely clear, there was no wind and the sun shone gloriously. We made good speed up the old track -- which was once the old coach road from Dolgellau to Llanuwchllyn and hence to Bala and beyond. Once up on the moor, though we were no longer climbing so steeply, the going was poor, with tussocky grass and boggy bits.

Owain and Osian looking for the best place to cross the river. Osian has drawn the short straw and ended up with the black wire. These reels are heavier, because they contain more wire. The outer electrodes on the black wires have to go the full distance of 100m. The inner electrodes only go as far as 20-30m

Once right up on the moor (Waun y Griafolen means Moor of the Mountain Ash, though there are no trees there now and the only signs of trees are the bits of wood preserved in the peat, which have been dated at 7,000 years old), the team set up the equipment. Graham operated the complicated bit in the middle, while I recorded the readings and shouted instructions to the two lads who disappeared off into the distance with the outer electrodes.

	Owain set off along the tape, vanishing into the distance with one electrode...
...while Osian set off in the opposite direction.