DR JEREMY BURGESS / SCIENCE PHOTO LIBRARY DR JEREMY BURGESS / SCIENCE PHOTO LIBRARY
A dry stone wall in Borrowdale Cumbria UK. Dry stone walls are widely used in Northern Britain as a durable stock-proof boundary to pastures. The materials used vary with availability, and may include river cobbles, clearance stones from pastures, and quarry stone or slate. The pictures shows the west-facing side of a wall 50m above sea level, built from a mixture of cobbles and clearance stones The rock is of the Borrowdale Volcanic series. The surface of a dry stone wall is a harsh environment; here, it supports a variety of crustose lichens, the most obvious being the lime-green Rhizocarpon geographicum, or map lichen. Lichens are the result of a symbiotic relationship between a fungus and an alga; this partnership is able to wthstand conditions of drought and extremes of temperature that would be fatal to either constituent on its own.
Model release not required. Property release not required.