424 



A\ 1 7 URE 



[Arigust 31, 1882 



sentially southern and western, do not range further north, or 

 into the German Ocean area, and this southern relation of the 

 fauna of the Lower Selsea deposit (Lutraria mud-deposit) is still 

 further strikingly illustrated by the presence of the before-men- 

 tioned two remarkable species, Peclen pilymorphus and Lutraria 

 rugosa, neither of which are now known to range further north 

 1I1 mi Lisbon. " We therefore have indications of a warmer condi- 

 tion of the waters of the English Channel, which allowed southern 

 forms to range to a more northern latitude than now, and then a 

 limitation of these forms to the area where now found, or in the 

 Sussex deposits." The inference drawn by Mr. Godwin-Austen 

 as to the manner in which the elephant's remains occur in this 

 Lutraria clay is an obvious and an interesting one, as it enables 

 us to arrive at a relative geological date, showing that the lower 

 estuarine beds of Selsea and of the Sussex levels generally were 

 contemporary with what is known as the period of the large 

 mammalian fauna. 



Overlying this Lutraria or mud deposit, there occurs a tough, 

 ca'crreous, sandy clay ; with chalk, and chalk flints — waterworn 

 and of large size. This Yellow 1 'rift clay is of marine origin, 

 determined by the associated molluscs ; I.ittorina and Mytilus 

 being disseminated through the mass. This deposit occurs over 

 the whole of the Sel-ea peninsula, and extends inland beneath 

 the Sussex levels. Besides the large masses of flints and ma- 

 terials from the chalk, oolitic rocks, and chert-sandstone from 

 the Upper Greensaml, resembling that occurring at Lyra: and 

 mouth, there are other rocks which, from their " ages, com- 

 position, origin, size, and condition," render the mode of accu- 

 mulation a problem of great geological interest. ''The rocks 

 in question consist of grey porphyritic granites, red syenite-, 

 syenite, hornblendic greenstones, mieha-schists, green fissile 

 slates, masses of quartz from veins, siliceous sandstones," such as 

 occur in the Palaeozoic series (Lower Silurian) of Normandy, 

 micaceous sandstone with orthides, probably from the Devonian 

 beds, and blocks of compact limestone, whether from the 

 Devonian series of Devon or the Cotentin (France), is 

 uncertain." 



In size these older rocks range from coarse shingle up to masses 

 of 20 tons weight, the granitic rocks being the most numerous 

 and of the largest dimensions. A mass of porphyritic rock was 

 exposed near Pagham by coast -line denudation, measuring 27 

 feet in circumference. Whence came they, and how brought, 

 or what the transporting agent beyond that of floating ice, we 

 know not. I must refer you to Mr. R. Godwin-Austen's original 

 paper for matter of the highest interest relative to the original 

 history of the yellow clay and the conglomerate bed, and later 

 deposits in Sussex, as well as other phenomena bearing up 

 present aspect of ■ this singular area — a description of the 

 complex nature of the structure of which would here be out cf 

 place, " What was the c mdition of the English channel as to 

 its coast-line when certain marginal accumulations were being 

 1?" To an wer this demands a profound acquaintance 

 with the old physical • lie district both of Northern 



France and Southern England. 



'/'he Brick-earth. — Above the yellow clay and mammalian 

 graveL, the highest or upper mo I deposit on the coasf, there 

 occurs a uniform bed of dark chocolate coloured unstratified 

 clay, averaging about 3 feet in thickness. This clay forms part 

 of that great layer of earthy matter which overlies all the gravel 

 and other beds of the Sussex levels, and is extensively used for 

 brickmaking. This brick-earth is a subaerial deposit, probably 

 he wash of a I urface under a greater 



rainfall than we have now. This deposit is conspicuously 

 shown along the shire, and forms the low cliffs of Brackle- 

 sham Bay. To this period Mr. Godwin-Austen refers the 

 " Combe rock" of Selsea. He then refers to the condition 

 of the English Channel area, at the period of the Crag- 

 deposits of the German Ocean. The author is disposed 

 to the belief that this Channel area was mostly in the con- 

 dition of dry land at the time that the area of the German 

 Ocean was occupied by the Crag sea. The peculiar molluscan 

 fauna of the Sussex deposits point to a limitation of a marine 

 province m that direction, whilst their habits indicate at the same 

 time shallow water and marginal conditions. The temperature 

 of the water of the English Channel during the period of the 

 Elephas primieenuis, and its associate-, was such as now occurs 

 12 degrees or nearly 800 miles further south. In 1871 Mr. 

 Alfred Bell examined with great care the fossil contents of the 

 Lutraria clay or mud-deposit ; he has added materially to the 

 hitherto published li ts of contents of this deposit. The result 



proves it to be unique as regards the fauna. "Of the 144 

 species of shells Mr. Bell states that 30 do not exist nearer than 

 the West of England, the Channel Islands, north of Spain, 8 

 or 10 not passing this side or north of Gibraltar, all being littoral 

 (or sub-littoral) species. As British Quaternary fossils 45 are 

 peculiar to Selsea, and 20 others probably find here their earliest 

 place in British geological history." Numerically the contents 

 of this mud deposit are as follows : mammalia, 5 genera and 6 

 species ; mollusca (bivalves), 33 genera and 62 species ; univalves, 

 32 genera and 80 species ; polyzoa, 2 species ; crustacea, 8 

 genera, and 10 species ; echinodermata, 2 genera and 2 species ; 

 foraminifefa, 9 genera and 10 species. Most of the fossils occur 

 opposite Thorney coastguard station, where the Lutraria clay 

 rises at intervals in low hummocks. The elephant remai is 

 appear to be those of E. antiquus. The tooth of E. i/icriJioualis 

 has also occurred here, an association resembling the Farest-hed 

 of Cromer. In the Chichester Museum there exists the greater 

 portion of a fine skeleton E. antiquus obtained from this mud 

 deposit. 



I have thus dwelt at some length upon these post- 

 Pleiocene or Pleistocene beds at Selsea, owing to their local 

 interest, and hope by so doing to induce any present who may he 

 interested in the Quaternary geology of the British Island-, 

 especially that of Sus ex, to visit Bracklesharn Bay and Selsea, 

 near to which we are now assembled. 



The Eocene Formations of Selsea and Bkacklesham 

 Bay. 



It is impossible to pass unnoticed the Eocene tertiaries that 

 occur in Bracklesharn Bay, the stratigraphical position of which 

 has long been settled, comprising the middle portion or fossilife- 

 rous division of the Bagshot Series. The Bracklesharn beds 

 take their name from the Bay in which they are so charac- 

 teristically developed, yet difficult to clearly understand. The 

 main divisions extend from Wittering, on the west, to the Barn 

 Rocks, east of Selsea Bill, a distance of seven miles. 

 The Hampshire basin alone, in England, contains the numtnulitic 

 series, no fossiliferous representative being known in the London 

 basin. 



About a mile to the east of Selsea Bill is situated the "Park 

 bed." This Park bed is analogous or equivalent to the " Calcaire 

 grossier" of Grignon, in the Paris basin. 1 It contains thousands 

 of Nummulina laevigata associated with Permc, Bullae, Cyprnea, 

 Solens, besides the well-known coral Litharea Websteri. The 

 Park bed is situated close to the shore, and is accessible at low- 

 water. It is here at low spring tides that the very recent 

 post-PIeiocene beds may be seen overlying the Eocene deposit. 

 At the Bill the Eocene beds are shown at low water in large 

 detached portions called the "Clibs," the larger portion lying to 

 the south-west, and the so-called "Mixen Rocks," marked by 

 the " Mixen Pole," trend about a mile out into the sea. From 

 i-t;s, which extend a mile and a half ea-t and west, and 

 varying from 200 to 400 yards wide, is procured the Alveolina 

 or foraminiferal limestone ; the "Clibs" rock contains scarcely 

 any other fossil remains. The Houngate Rocks, the same as the 

 Mixen. are situated opposite Old Thorney Station House, and are 

 visible at low water ; they are nearly a mile in extent, and vary 

 from 50 to 60 yards in width. Certain fossils have given ns 

 to the beds that range through the bay. The remarkable shells 

 Cy/iu-a Coomlni, the great Co it it cum (C. giganteum), and C. 

 cornucopia, Vencricardia planicosta Turritel'a tcrcbcllata Couus 

 diadema, &c, amongst many others, aid us to determine 

 the beds stratigraphically— locally the "Barn bed," "Palate 

 bed," " Venericardia bed," the "Park," &c , serve to mark 

 horizons of importance. 



Opposite the New- Thorney Station are the Scrobicularia or 

 Lutraria clays or mud deposits from which the elephant remains 

 were obtained. 



The Rev Osmond Fisher, in his description of the "Brackles- 

 harn beds" of the Isle of Wight basin, restricts the name to a 

 group of strata rich in organic remains, the greater part of which 

 are displayed at low water upon the shore at Bracklesharn Bay 

 in Sussex. He also includes under that name higher beds than 

 any seen at Bracklesharn Bay that occur at Stubbington and the 

 New Forest. He groups certain strata which appear to inter- 

 vene between the base of the Barton series and the highest beds 

 at Bracklesharn Bay on account of their containing an assemblage 



1 Four hundred species of Mollusca have been found in the French 

 deposits. 



