IX. — Geological Sketch of the North-western Extremity of Sussex j and 

 the adjoining Parts of Hants and Surrey. 



By Roderick Impey MURCHISON, Esq. Sec. G.S., P.R.S., &c. &c. 



[Read December 16th, 1825.] 



1 PROPOSE to illustrate in this memoir the order of superposition of the 

 strata in that north-western part of Sussex which is bounded on the south 

 by the chalk escarpment of the South-downs^ and in those adjoining parts of 

 Hampshire and Surrey which are bounded severally, on the west by the Alton 

 chalk-hills, and on the north by the North-downs. 



Having- examined a portion of this country with my friend Dr. Fitton, I 

 was encouraged by him to attempt an exact delineation of the whole, by colour- 

 ing the Ordnance map according to geological formations *. This task being 

 now accomplished, I beg to lay the result before the Geological Society, 

 together with such illustrative specimens of the strata and their fossils as I 

 have been able to collect in the course of last summer. 



The formations of which this district is composed, begin to emerge from 

 the superior strata at the northern extremity of the parish of Bentley in Hants, 

 6 miles north-east of Alton ; and they range from thence to the south and 

 east, until their escarpments are cut through by the Arun, which river I have 

 chosen to make the limit of my present observations. 



The chalk escarpments of the Alton hills and of the South-downs, converg- 

 ing towards Pelersfield, are united at an acute angle in the parish of East 

 Meon, 4 miles west of the former place ; and within that angle the inferior 

 strata are disposed conformably. Hence by assuming the Weald clay in the 

 little valley of Harting Combe as the nucleus of the district, a regular succes- 

 sion is developed up to either chalk-range, and the breadth of each interme- 

 diate formation which mantles round the Weald clay, is shown by the map and 

 section annexed. 



The same order of superposition having been clearly established in the 



* PI. XIV. is a sketch taken from the coloured copy of the Ordnance map alluded to in 

 the text. 



VOL. II. SECOND SERIES. O 



