Geoscience Reference
In-Depth Information
published in Oxford in 1707, but unfortunately the remaining pro-
posed volumes never appeared. Travels were not without their diffi-
culties. Usually he had three assistants with him, but one absconded
in Wales. In Cornwall the remaining trio were arrested in the town of
Helston where they were accused of stealing. Having managed to
extricate himself and his companions, Lhwyd probably felt that noth-
ing worse could befall them. Nothing worse? In Brittany the following
year Lhwyd was arrested and charged with being a spy - a very serious
charge - but fortunately after a spell of ten days spent in prison at Brest
he was released on condition that he left France immediately. One
would imagine that he was happy to comply. He then returned to
Oxford and began to write up his travels.
In the context of this story, he was perhaps an unwitting con-
tributor to the later debate on the age of the Earth. As we have heard,
he travelled widely, particularly in Wales. At some point before 1691
he ventured up Snowdon, the highest peak in the northern mountai-
nous region. He collected plants including the Snowdon lily, Lloydia
serotina, which today is very rare indeed in Britain with only five
patches clinging precariously to the slopes. Lhwyd was the first nat-
uralist to note that Britain's higher peaks supported a distinctive
alpine flora. Today Lloydia thrives in the Alps, the Himalayas, in
Alaska and in northern Siberia.
The pass at Llanberis is regularly used by hikers in the region,
and allows relatively easy passage to higher slopes. Underlain by
Cambrian sediments and coarse intrusive granites and other igneous
rocks, the valley is steep-sided, flat-bottomed and most impressive
(Figure
4.3
). Now certainly Lhwyd would not have appreciated its
origins as a glaciated valley - the recognition of past glaciers in Great
Britain and Ireland did not come until 150 years later with the visit by
Louis Agassiz in 1840 - but he was intrigued by the large boulders that
lay on the valley floor, and on that of the adjacent valley of Nant
Ffrancon. On 30 February 1691 he wrote to his friend John Ray
(1627-1705), who had earlier written about erosion on the surface of
the Earth and who found it difficult to imagine that geological time
