Rcvleivs — Gcoloijy of Hcnlcij-on-Thamca. 39 



a locality made famous by Mr. Joseph Steveus in " A Descriptive List 

 of Flint Implements found at St. Mary Bourne ", 1867. 



The memoir on Henley on-Thames includes brief descriptions of the 

 Kimeridge Clay, Portland Beds, and Lower Greensand which occur iu 

 the north-western portion of the area ; but the bulk of the work is 

 taken up with detailed accounts of the Upper Cretaceous rocks and 

 fossils by Mr. Jukes-Browne, and of the Eocene and superficial 

 deposits by Mr. Osborne White. The Chalk forms the dominant 

 features over more than half of the area, and the junction of the 

 middle and upper divisions occurs along the crest of the Chiltern 

 Hills, overlooking the Thames Valley at Wallingford on the west 

 and sloping towards Henley-on-Thames on the south-east, with 

 a marked inlier of Middh^ Chalk bounded by the locally prominent 

 Chalk llock between Stokenchurch and Henley. This last-named 

 feature is shown on a special map in the memoir, as the Chalk Rock 

 was found by Mr. Osborne White to occur over a larger area than was 

 depicted on the colour-printed map. Eocene formations (Reading 

 Beds and London Clay) occur only as outliers, as in the picturesque 

 regions of Xettlebed and Lane End. 



Those concerned in studying the origin and history of the Thames 

 Valley will find mucli to interest them in Mr. White's chapters on the 

 Scenery and Superficial Deposits. His record of the occurrence of 

 (^uartzose gravels in the Reading Beds of Lane End is noteworthy in 

 connection with the origin of the 'Pebble Gravel'. In his opinion 

 this much debated deposit may be ascribed mainly to the Avasting of 

 Lower Eocene pebble-beds, a process that may have commenced in 

 Oligocene times and have continued ever since. The Clay-with-flints 

 likewise has a long history, when regarded as "a product of the 

 decomposition of the Chalk and the disintegration of the Eocene and 

 later sediments formerly covering that rock ". 



With regard to the Plateau Gravels, they are divided by Mr. AVhite 

 into the * Quartzite Gravel ', characterized by liver-coloured and grey 

 (juartzites from the Banter, and the possibly newer ' Angular Flint 

 Gravel'. He observes, " That the quartzitic Plateau Gravel bordering 

 the Thames Valley is largely of lluviatile origin can, however, hardly 

 be doubted ; and, although proof is lacking, the present writer is 

 much disposed to think that the exotic material which occurs so 

 abundantly in that drift, and which, in the Henley district, appears 

 at first in rounded stones of small'size in the upland Pebble Gravel, 

 400 to 500 feet above the Thames, was being carried into the region 

 of the Upper Thames basin long before the commencement of the 

 Pleistocene ' Ice Age '. " 



Mr. White further remarks that "The gravel is decalcified and, 

 save for a few pala^oliths, has yielded no fossils. As to its age, little 

 is certainly known. The lower tei'race deposits — i.e. those up to 

 200 feet above the level of the Thames in their neighbourhood — are 

 probably all of Pleistocene date ; the highest may be of Newer Pliocene 

 age ". The.se conclusions are of great interest, an<i will be helpful in 

 all studies of the Thames Valley. Some of the Palaeolithic implements 

 above referred to have been found in Friar Park, Henley. 



