Classification of glacial valleys

 

 

 

 

Glacially-overdeepened valleys in south Hoy, occupied by the Heldale and Hoglinns Waters

 

Images courtesy of Alan Moar

 

 

 

 

 

 

 

 

Glacial breaches in north Hoy

 

Glacial Valleys

Aside from Hoy, the low, open valleys between ridges and which lie submerged the floor of the sounds are products of ice sheet erosion, with deformation of ice around high ground. On Hoy, the high ground is dissected by through valleys. In south Hoy, the valleys breach the preglacial watershed, with development of rock basins, now filled by lochs, where ice has been forced through narrow cols. The deep through valleys also reflect the penetration of tongues of ice within former ice sheets and the breaching of the watershed. Here, however, the valleys may have a compound origin, with initiation of deepening by corrie glaciers sourced on the high ground.