deep weathering

erosion surfaces

tors in Caithness

 

The Maiden Pap,   an inselberg with subdued summit tors developed in Devonian conglomerates

 

Image by Alan Moar

 

 

 

 

 

 

 

 

 

 

 

Godard's (1965) section of the Maiden Pap, showing the relationship between the Devonian cover rocks and the underlying slopes

 

 

Inselberg

Definition: a prominent steep-sided hill rising above a plain. From the German, meaning "island mountain"

The chain of inselberg in southern Caithness form some of most striking hill scenery in Scotland, comparable to the better known Torridonian Sandstone hills of Assynt. On the clearest days, the cone of Morven is visible across large stretches of the Northern Highlands, from Hoy and even from south of the Moray Firth.

Inselbergs may be divided somewhat arbitrarily into those of position and those of resistance. Inselbergs of position have become isolated as erosion has led to the retreat of a major escarpment - Monument Valley in Utah presents classic examples. Inselbergs of resistance develop on rocks which weather and erode more slowly then the surrounding rocks. In Scotland, Mormond Hill in Buchan is a fine example, a quartzite residual rising from the surrounding granitic and metamorphic rocks.

The inselbergs of Morven, Smean and the Maiden Pap are developed in a Devonian conglomerate rich in rounded pebbles of quartzite and granite. The conglomerate is firmly cemented and its most resistant masses form tors and lines of cliffs. Although the conglomerate was originally more extensive, the beds forming the Maiden Pap occupy the former core of a syncline and provide a neat example of topographic inversion where the down fold has ended up as a hill due to its closed fractures. So these inselbergs are hybrid forms. The ridge of Scaraben is unequivocally residual, developed in quartzite. Like several of the other lower quartzite hills, its slopes are mantled by Devonian breccias which represent consolidated and once deeply buried ancient screes. The summit and northern face of Scaraben lack these breccias covers and it seems that the ridge is a product of Tertiary erosion.

The flanks of Morven and Maiden Pap have been over-steepened by glacial erosion. Screes formed of enormous blocks of conglomerates mantle the benches and lower slopes (Crampton and Carruthers. 1914).