Page 211 - Fundamentals of Geomorphology

194 PROCESS AND FORM

Plate 8.1 Rillenkarren formed on a limestone block in a
Holocene landslide pile, Surprise Valley, near Jasper, Jasper
National Park, Alberta, Canada. The blocks are chaotically
orientated in the pile, but are rilled down the modern
drainage lines.
(Photograph by Derek C. Ford )

in diameter. Larger ones merge into solution pans.
They occur under soil and on bare limestone. Along
with shafts, they are the most widespread karren form.
Many are transitional to shafts. Solution pans or solu-
tion basins are small depressions shaped like basins or
dishes, usually with a thin cover of soil or algal or vegetal
remains. They are no more than 3 m wide and 0.5 m Plate 8.2 Decantation runnels (Rinnenkarren) on marble
deep, but many are much smaller. Some of the carbon near Pikhauga Ridge, Svartisen, Norway.
(Photograph by Derek C. Ford )
dioxide released by the decaying organic matter dissolves
in the water collected in the pans and boosts their dis-
solution. The Slav term for them is kamenice (singular runnels (Rundkarren) are the same size as ordinary
kamenica), and the American term is tinajitas. Undercut runnels but they are worn smooth by the active cor-
solution runnels (Hohlkarren) are like runnels in form rosion identified with acid soil waters. They are visi-
and size, except that they become wider with increasing ble only when the soil or sediment blanket has been
depth, probably owing to accumulated organic matter or stripped off (Plate 8.3, foreground). Cutters are soil-
soil keeping the sides and base near the bottom damp. covered clints that are widened at the top and taper
Solution notches (Korrosionkehlen) are about 1 m high with depth (Colour Plate 2, inserted between pages
and wide and 10 m long. They are formed where soil 208 and 209). Solution pipes (or shafts or wells)are
lies against projecting rock, giving rise to inward-curved up to 1 m across and 2–5 m deep, usually becom-
recesses. ing narrower with depth, but many are smaller. They
Covered forms develop under a blanket of soil are cylindrical or conical holes, occurring on such soft
or sediment, which acts like ‘an acidulated sponge’ limestones as chalk, as well as on the mechanically
(Jennings 1971, 48). Where it contacts the underly- stronger and less permeable limestones. Solution pipes
ing limestone, the ‘sponge’ etches out its own array of usually form along joint planes, but in the chalk of
landforms, the chief among which are rounded solu- north-west Europe they can develop in an isolated
tion runnels and solution pipes. Rounded solution fashion.