412 PEOCEEDIN'GS OF THE GEOLOGICAL SOCIETY. [JunO 23, 



refer to different portions of it near mid-tide level, or to the same 

 portions modified by fresh sections being exposed at different times 

 by the sea : — Sonth of New Pier the Lower Boulder formation cannot 

 be easily described. Within a small compass it seems to vary both 

 in vertical and horizontal succession — ^in one place a fine, uniform, 

 tough, and bright yellowish-brown clay more or less laminated, in 

 another a fine loamy sand — here a rather solid brown clay with a 

 grey marly or shaly fracture, there a coarse sand charged with stones. 

 But you cannot travel far without seeing these variations of structure 

 graduating into, or succeeded by, the main character of the forma- 

 tion, namely a very hard brown clay generally full of subangular 

 and rounded stones, varying from the smallest size up to boulders 

 commonly so called. They consist of porphyry, granite, &c., the 

 proportion of igneous and metamorphic rocks being greater than in 

 the upper clay. The loose pebbles on the beach would here appear 

 to have come chiefly out of this formation ; and to it may be traced 

 nearly all the large boulders which occur at intervals. Some of 

 these boulders reach the size of 5 feet in diameter. Many of them 

 continue firmly fixed in the clay, where they have probably remained 

 since they were first imbedded. The sea washes the clay from 

 around them, and by the gyratory action of its waves excavates cir- 

 cular depressions ; and in this way it has probably succeeded in up- 

 rooting and displacing some of the boulders* North of Blackpool 

 Old Pier, a fine clay, loam, and hard stony clay similar to the above 

 make their appearance under mean- water level. A short distance 

 to the south of the Gynn, in the bed of the sea, the fine bright yel- 

 lowish-brown loam exhibits oblique and curved lamination, the thin 

 layers cropping out around small synclinal basins. Further north, 

 near Uncle Tom's Cabin, the finer part of the Lower Boulder formation 

 assumes the form of a laminated reddish brown sandy loam nearly 

 as solid as rock. Beyond Uncle Tom's Cabin a similar deposit may 

 here and there be seen at low water ; but there, as on the south 

 beach, it graduates into the prevailing hard stony clay. Along the 

 whole shore, nearer to the cliff-line, the hard stony clay may be traced. 

 It is probably a higher bed than the one containing fine clay and 

 loam ; and a great part of it would appear to have been recently 

 denuded. Of its former thickness, at least in some places, one may 

 form an idea from coast-sections north of Uncle Tom's Cabin. 

 Under the middle sand and gravel, and separated from this formation 

 by a distinct line of demarcation, the hard stony clay rises in two 

 places above the base of the cliff, as represented in figs. 3 and 4. In 

 the most northerly instance the lower part of the cliff, to the height 

 of at least 20 feet, is composed of it. It likewise forms the solid 

 floor of the beach for some distance seaward f. This is a favourable 



* During the very high tides of January and February 1869, according to 

 newspaper reports, several large boulders were displaced, and one of them thrown 

 up on the promenade. 



t Northwards it disappears under the dipping sand-beds of the middle drift. 

 In the clijffs further south a removal of the talus might reveal sections in addi- 

 tion to those I observed. 



