358 



Mr. Lyell on the Boulder Formation, 



the wall of chalk are vertical, (see diagram, fig. 8.) yet the 

 beds of the same formation have but a moderate inclination 



Fi.£T. 7. 



Northern protuberance of chalky Trimniingham. 



a. Chalk with flints. 



b. Gravel of broken and half-rcunded flints. 

 e. Laminated blue clay. 



in the lofty cliff behind. A layer of chalk flints in situ shows 

 that the stratification of the chalk itself is nearly vertical at 

 least in one place, although the beds seen in a large cave facing 

 the sea show a slight curvature only. Where the chalk joins 

 the drift on the southern or Mundesiey side of the promontory, 

 I observed in 1839, at the junction, 1st, a portion of the chalk 

 itself decomposed, then a vertical bed of gravel, {g, fig. 8) 

 30 feet high and several feet thick, then dark blue clay with 

 white chalk pebbles, then sandy, and then other beds of or- 

 dinary drift. Some of these disturbed beds contain fragments 



Fio-. 8. 



drift. 



g. gravel. 



chalk. 



t. talus. 



Side view of the same. 



of marine crag shells, as Cijprina, Cardiu?n, Tellitia, &c. I 

 have stated in the Principles* that this mass of chalk at its 

 northern edge, or towards Trimmingham, actually overlies 

 some beds of blue clay or drift as at the right hand extremity 

 of fig. 7. Now this remarkable superposition was still evident 

 in June 1839, notwithstanding the unusual height of the sea 



* Vol. iii. p. 180, 1st edit., and vol, iv. p. 86, 5th edit. 



