280 Notices of Memoirs — 



and joins the Thames near Oxford to the south; the valley in which 

 it flows gradually narrowing in that direction, while to the north it 

 is spread out, and almost divided into two portions by a ridge of 

 Lias Marlstone ; extending from Hardwick to Fenny Compton, this 

 formation also forms the table-land on either side of the valley. 



The lowest zone of the Lias visible at Banbury is that of Am- 

 monites Henleyi, from which beds the author obtained 103 species of 

 fossils and a large number of Foraminifera ; he describes the beds as 

 consisting of dark-blue shaly marls, with occasional septaria and 

 nodular phosphatic concretions, with a thin bed of hard grey shelly 

 Limestone near the top, known as " Banbury Marble." 



From the Capricornis zone, visible in the brick-yard, by the west 

 side of the canal, south of the town, he obtained 25 species, amongst 

 them Cardium truncatum, Modiola cuneata. The Am. Jamesoni, 

 Senleyi, and Capricornis zones the author calls the Lower Middle 

 Lias, to distinguish them from the Marlstone rock-bed and its 

 underlying marls ; the lastx two zones he considers to be forty feet 

 in thickness. 



His Upper Middle Lias is made up of the Am. margaritatus beds 

 of Twyford Wharf, south of Banbury, with 40 species of fossils, and 

 the Marlstone rock-bed or zone of Am. spinatus, which is about 

 twelve feet in thickness, and forms a broad table-land on the south 

 and west, and a terrace on the east side, the disintegration of which 

 has formed the rich red wheat-growing land, described by Arthur 

 Young " as the glory of Oxfordshire." On Edgehill escarpment it 

 rises to an elevation of 720 feet above the sea-level, dipping down 

 to 500 feet at Banbury. 



The following section is given of the Marlstone at the King's 

 Sutton ironstone-works : — 



Soil, sandy and ferruginous 



Upper Mhynchonella tetrahedra bed (Marlstone) 



Marlstone 



Lower Ehynchonella and Terebratula bed (Marlstone) 



Marlstone with concretions 



Eusty ferruginous concretions 



Sandy blue marl and grey shale 



The concretionary nodules are rich in phosphates, and are, no 

 doubt, partly the cause of the fertility of the marlstone soil. Silicate 

 of iron grains often occur, so as to give almost an Oolitic structure 

 to the Marlstone ; these grains are sometimes hollow, and appear to 

 have been moulded upon the shells of Foraminifera and Entomo- 

 straca. The rock-bed is a sandy ferruginous limestone, brown out- 

 side, and greenish blue in, separated by thin partings of sandy loam 

 and clay. North and west of Banbury the rock becomes thicker, 

 and is largely quarried for paving, troughs, and gravestones. The 

 Hornton stone has been much used in the old churches, and wears 

 well. 



Large excavations have been made in the marlstone on both sides 

 of the valley at Adderbury and King's Sutton, four miles south of 

 Banbury, near the Great Western Eailway and Canal, for the 

 purpose of smelting to obtain the iron which is found in the Marl- 



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