Back to Barwick Monday, 26th January 2004
But I'm soon back to pathfinding and, as part of this walk zig-zags across open fields, my directions read like a treasure map of the featureless stubble:
Potterton BeckPotterton Beck flows down a fold in the ridge from a scrubby piece of woodland by the A64, marked 'Jacob's Well' on the map. As I walk upstream at first the beck is well defined, flowing amongst the trees to my left, but when I come to a small piece of rough ground, disturbing a few sheep, the stream bed, now a shallower, grassy v-shaped ditch, is bone dry.
At the other side of the rough ground the stream appears again, narrower but flowing as normal. There's no sign of a man-made culvert so I guess the stream has carved itself a channel underground: dissolved itself a channel underground might be a better way to put it, as slightly acid rain or groundwater can, over time, dissolve limestone. Magnesian Limestone
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A
flask of coffee gives me a welcome excuse for a pause at the halfway
point on a walk I'm checking out at Barwick in Elmet,
east of Leeds. I find a bough of a hawthorn to sit on at a corner
of Kiddal Wood, which seems especially peaceful
in comparison with the busy A64 Leeds-York road that runs alongside
it.
When
I'm checking walks I miss a lot of the wildlife because I'm so focused
on the directions. Within a few minutes a nuthatch
flies to the trunk of the old oak tree in front of me.
One
signpost stands on the crest of a ridge on this magnesian limestone
scarp. Three lapwings fly off as I stomp towards
it along the narrow path across the winter wheat.
The
creamy coloured magnesian limestone of this ridge
was laid down in a dying sea some 250 million years ago in the Permian
period when Britain was in a desert region of the supercontinent
Pangaea. Magnesian limestone contains dolomite,
CaMg(CO3)2, a double
carbonate of magnesium and calcium. 
