28
John Skinner informs me that he made two new
County records for the crustose lichens
Arthonia lurida and Pertusaria leioplaca on
the smooth bark of sweet chestnut trees.
Tony Boniface
The Influence of Geology on Slopes and the
Problems of Road Building in the Weald of
Kent. 26th June, 1983
From Sevenoaks Station the party proceeded to
Panthurst Farm lay-by on the Sevenoaks By-Pass
(A 21). At this site several lobes of debris
(solifluction lobes) caused by a shallow form of
landsliding in cold, wet conditions when
glaciers occupied more northerly parts of
Britain were pointed out. The original line
of the A 21 was indicated, passing over 7 out of
the 8 lobes in the area. During construction
of the road the workings caused 2 of the slides
to be reactivated. As a consequence, the road
had to be re-aligned off the lobes and a bridge
re-constructed to accommodate the new line of the
road, at great expense.
At St. Julian's Farm, a lobe was examined in
more detail and it was seen that not only was the
lobe subject to gross movement as a unit, but
that parts of the surface of the lobe were subject
to localised movement also, as occurred naturally
in the earlier part of this century.
After lunch the party visited High Rocks, Tunbridge
Wells. Here Tunbridge Wells Sandstone was noted
to be resting on clay which provided an unstable
base. As a consequence, the sandstone has broken
into large blocks which have slipped apart on the