The chief geological feature of the farm park is Ordovician Rock. This consists of an attractive dark blue-grey slate that can be seen most clearly on the cliff faces. It is sedimentary rock originally lain as a marine sediment, hence its layered structure. Geological movement in the distant past turned these layers on their sides so that they are now at almost 90 degrees to the horizontal. This layered structure accounts for the many caves below the farm park as the forces of nature - freezing percolating rain water in the cold winters and the constant pounding waves of the sea - gradually, over thousands of years, erode the rock, allowing voids, or caves, to be formed.

This erosion also caused the island to be formed as the sea gradually ate its way through softer areas of rock. Later on, ice age glaciations, the last about 10,000 years ago, blocked the mouth of the River Teifi, thereby forming 'Lake Teifi' as far inland as Lampeter. During this period 'LakeTeifi' is thought to have drained to the sea via the Nevern valley, the Gwaun valley and the western Cleddau into Milford Haven. The glaciations deposited gravels and rounded stones here. Some of our fields have gravel deposits more than 30 feet deep. Stones, rounded by the sea, consisting of rocks from Northern Ireland and beyond, can be found all over the farm. Sometimes they can be 5 feet or more in diameter. It can often be a problem to remove them, which is necessary, since they damage the farm machinery.

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