196 
PLUMP TON ROCKS (see Photograph). BY THE EDITOR, 
The subject of the photograph issued with this volume of 
Proceedings has been chosen to illustrate the extensive 
denudation which has taken place in the upper rock of the 
Third Grits. The series of Millstone Grits so denominated 
extend in a semicircular line from southern Yorkshire along 
the crest of the Pennine chain of hills north-west of Halifax 
to Plumpton and Brimham. In the northern part the sand- 
stone is decidedly red in colour, and from its uneven hardness 
is very liable to weather, or become decomposed by the action 
of atmospheric agencies, into all kinds of peculiar forms. 
Examples of this action may be seen in several localities, 
notably at Brimham and Plumpton. At Brimham the justly 
celebrated Rocks cover a large area, and have assumed a 
variety of peculiar forms. Fine examples may also be seen 
on the roadside between Knaresborough and Spofforth. At 
St. Francis Chapel a large mass of red sandstone stands alone 
in a field, the surrounding part being disintegrated, and 
forming the soil. The sandstone is very thick-bedded and 
massive, it contains a large amount of felspar, the red colour 
being principally due to iron. It forms a serviceable build- 
ing stone where of good quality, but it exhibits a tendency 
in manjr places to pass into purple sandy shales. The pic- 
turesque masses formed by weathering are probably due to 
this tendency combined with the ease with which the felspar 
is decomposed. The rocks in Plumpton Park are perhaps 
the most beautiful example of the effects of this action. They 
cover a large area, and advantage has been taken of their 
situation to construct an artificial lake, from the bed of which 
the rocks rise perpendicularly, as seen in the photograph. 
Trees also lend their graceful charm to the scene, and afford 
