Causey Pike Fault

The Causey Pike Fault or Causey Pike Thrust is a major WSW-ENE trending fault within the Lower Paleozoic rocks of the English Lake District.

The Causey Pike Fault has been recognised across the entire outcrop of the Lake District inlier, extending about 35 km from near Ennerdale Bridge in the west, to near Troutbeck in the east.

A possible continuation of the fault to the east has been recognised in the Cross Fell inlier, where it also juxtaposes two differing parts of the Skiddaw Group.

The fault is described as a thrust near Causey Pike, where metasomatised rocks of the Crummock Water Aureole are emplaced over sandstone olistoliths of the Buttermere Formation, but the overall displacement on this structure is oblique, with a significant component of sinistral (left lateral) strike-slip motion.

The oblique slip movement on the fault occurred during the Acadian Orogeny, at least in part postdating the contact metamorphism that caused the development of the Crummock Water Aureole (dated to about 401 Ma - Emsian), which itself postdates the formation of the regional cleavage seen within the Skiddaw Group.

The Causey Pike Fault visible at the base of the crags on Causey Pike and across the flank of Scar Crags , viewed from Ard Crags
Rocks of the Crummock Water Aureole, thrust over a sandstone olistolith of the Buttermere Formation, just below the top of Causey Pike