1865.] 



Notes and Correspondence. 



361 



duce, both in Oxfordshire and 

 Northamptonshire, a sihcious iron 

 ore capable of being worked. In 

 the former county, however, we 

 only know of one spot where it is 

 of any commercial value — we refer 

 to the village of Steeple Aston, near 

 Deddington ; but even here we 

 should infer, from the character of 

 the ore, that it would be capable of 

 producing only exceedingly brittle 

 iron. Having thus briefly dis- 

 posed of these unimportant ores, 

 we now proceed to the third, and 

 the only commercially valuable iron 

 ore in Oxfordshire — this is the rock 

 of the Middle Lias, or Marls tone. 



This remarkably persistent rock, 

 extending as it does from the south 

 coast of England, through Somer- 

 setshire, Gloucestershire, Oxon, and 

 Northamptonshire, to the York- 

 shire coast, though never of greater 

 thickness than twenty or twenty- 

 five feet, and often less than a 

 third of that amount — is, in certain 

 places, a calcareous sandstone ; in 

 others, a valuable ironstone. Un- 

 der the former character, it may be 

 traced along the western flanks of 

 the Cotteswold range of Somer- 

 setshire and Gloucestershire, often 

 jutting out from the sides of the 

 hills in the form of terraced or 

 tabulated banks, subsidiary to the 

 main ridge. In this district, how- 

 ever, it is never an ironstone, but 

 a highly calcareous sandstone, 

 crowded with characteristic fossil 

 shells. On being traced, however, 

 into Oxfordshire and the neighbour- 

 ing districts to the north-eastward, 

 it becomes more or less impreg- 

 nated with iron, till it assumes the 

 character of a nidious peroxide or 

 carbonate, with a proportion of 

 metal varying from 20 to 40 per 

 cent. The rock rests generally on 

 certain sandy shales, more or less 

 pervious to water ; and is sur- 

 mounted by the blue clays and 

 shales of the Upper Lias, which 

 separate it from the Great Oolite. 

 The thickness of these shales 

 varies from 20 feet at Fawler, near 



Charlbury, to about 120 feet in the 

 neighbourhood of Banbury, and 

 they often form sloping grassy 

 banks, rising above the terraced 

 surfaces of the Marlstone rock. In 

 the Cleveland hills, the iron-bed 

 occupies a precisely similar geologi- 

 cal position, underlying the blue 

 shales of the Upper Lias, which are 

 about 150 feet in thickness, and are 

 in turn surmounted by the free- 

 stone of the Grpat Oolite, which 

 forms the crest of the hills. 



In both districts the mineral 

 character of the ore is very similar. 

 In the hills overlooking the estuary 

 of the Tees, the ore, when hewn 

 fresh from the interior of the hill, 

 is of a greyish-green colour, and 

 very solid, but gradually passes, on 

 approaching the surface, into a 

 rusty and somewhat concretionary 

 stone, due to oxidation and weather- 

 ing. In Oxfordshire, the rock 

 assumes a deep olive-green colour, 

 and under the lens, shows an Oolitic 

 structure ; on exposure, and at the 

 surface, it also becomes rusty and 

 somewhat concretionary : and in 

 both cases, when calcined, it as- 

 sumes a red colour resembling 

 earthy haematite. In the Cleveland 

 hills, however, the ironstone rock 

 appears to be more persistent and 

 uniform in mineral character than 

 in Oxfordshire. 



The ore occurs, and was first dis- 

 covered at Fawler, near Charlbury, 

 about six years ago, on the property 

 of the Duke of Marlborough, along 

 the line of the West Midland Rail- 

 way. Considerable quantities have 

 been sent into South Staffordshire, 

 but owing to the depressed state 

 of the iron trade, it is not, we be- 

 lieve, being worked at present. 

 The rock is here about 12 or 15 

 feet in thickness, nearly uniform 

 in character throughout ; but in 

 some places somewhat calcareous. 

 An analysis made by Dr. Percy, 

 at the Museum of Practical Geology, 

 gave an average from nine samples 

 of 32 per cent, of iron, and of phos- 

 phoric acid only a trace. For flux- 



