DESCRIPTION AND CORRELATION OF THE BOURNEMOUTH BEDS. 209 
16. Descriprion and CorRELation of the Bournrmouta Brps.— 
Part I. Upprr Marine Sertus. By J. Srarxim Garpner, 
Ksq., F.G.S. (Read February 20, 1878.) 
Descriptions of the coast-section between Highcliff and Bourne- 
mouth, with which the present paper deals, have already appeared 
in the publications of the Society. That by Sir Charles Lyell*, in 
1826, was written when the strata included in this section were 
still supposed to belong to the Plastic Clay underlying the London 
Clay. In it the different beds forming Christchurch Head are care- 
fully distinguished, and their superposition illustrated in a somewhat 
idealized section. The description of the eight miles of cliff from a 
mile beyond White Pits to Poole Harbour is, however, dismissed in 
a very few words :—The “ section presented by the cliffs is continued 
so precisely in the line of bearing of the strata, that no new beds 
rise up, and it 1s unnecessary to describe them in detail. .... The 
prevailing character of the strata throughout this extent of coast is 
fine white sand; but yellowish and pinkish beds of sand occur, and 
thinly laminated clays in great abundance, resembling in appearance 
many of the light-coloured argillaceous marls of Montmartre near 
Paris; but in none could I discover any organic remains, except 
vegetable impressions, aud these very indistinct.” The proofs of 
origin, whether marine or freshwater, are considered equivocal. ‘The 
total thickness of the series, nowhere exposed to view, is put down at 
“not less than 150 feet.” It is also suggested that the argillaceous 
strata with shells of Alum Bay ‘are probably concealed here at 
some of the interruptions of the section.” 
The next description of these cliffs is by Professor PrestwichT in 
1848, written principally with the view of determining ‘“ the exact 
position which they bear with reference to the Barton Clay” (I. ¢. 
p. 43). He begins, however, with the assumption that Barton Clay 
is found to the west of Christchurch Harbour, and thence is led to 
place the strata of Christchurch Head higher in the section than I 
am inclined to do.. He compares a section of the Head with that of 
the Barton Cliff near its western termination, and concludes that the 
beds with septaria common to both are upon the same horizon. A 
mile and a half to the west of the Head a small lens-shaped section is 
considered to be “ aslight throwing in of an overlying stratum,” and 
evidently presenting ‘‘in a small depression the base of the Barton 
clays” (p. 47). The Eocene pebble-beds taken for diluvium by Lyell 
are carefully separated from the overlying angular gravel by Prest- 
wich ; but it seems that he thought them to be more continuous than 
they now appear to me. 
In 1861, the Rey. Osmond Fisher wrote ¢ defining the horizons into 
* Trans. Geol. Soc. ser. 2, vol. ii. p. 279. 
t Quart. Journ. Geol. Soc. vol. y. p. 43. { Zbid. vol. xviii. p. 65. 
