139 
ice, during the gradual subsidence of the land, and that the 
largest stones may often have been thrown up to the highest 
levels — as we, indeed, find on ordinary sea coasts. What would 
take place to a limited extent on a sea coast at a stationary 
level might take place to an indefinite extent on a sea coast 
progressively embracing a whole hill side. In the north-west 
part of Yorkshire, boulders may be found which must have 
come from a lower level. I have found them on the hill north- 
east of Settle ; and other instances might be mentioned in 
which land ice would not afibrd a satisfactory explanation of 
the phenomena. I may here remark that the glaciated rock- 
surfaces I have seen in the millstone grit district are on or 
near the summits of moors (though they are probably not 
absent from lower levels), as on Harden Moor, near Keighley 
(where I believe they were first discovered by the geological 
surveyors), and on E-ombald's Moor. On the highest plat- 
form of Harden Moor the rock is glacially planed, and on the 
summit of the north cliflP-line of Rombald's Moor, west of the 
headland called The Calfy the rock (very lately exposed under 
a bed of typical brown boulder clay) is beautifully planed, 
polished, and striated in a direction due west and east at a 
height (about 900 feet above the sea) and in a position 
relatively to the surrounding ground which forbids the idea 
of its having ever been reached by a valley glacier. During 
the gradual rise of the land, the yellowish-brown boulder- 
clay may have received additions in some places, while in 
others it may have been washed down the hill sides. The 
stones and boulders would become more and more rounded 
towards the bottoms of the valleys, until they graduated into 
accumulations of boulder- gravel, such as those seen around 
Bingley. 
3. Derivation and Mode of Accumulation of the Stratified 
Sand and Washed Gravel. — The blue clay appears to have 
undergone a certain amount of denudation before the yellow 
