52 Transactions of the 



were lined with mammillated, botryoidal, and semi-crystalline 

 fibrous limonite, and partially filled with stalactites. 



I have observed that in all cases the stalactites hang per- 

 pendicular to the actual horizon. As the cavities in which they 

 occur are in beds dipping at an angle of 48°, this conclusively 

 proves that the beds were tilted into their present position before 

 the iron was introduced. 



This observation is not limited to the stalactites, but also applies 

 in many cases to solid lumps of haematite penetrated by veins of 

 quartz, which are also perpendicular to the horizon. 



If then, as seems most probable, the overlying horizontal beds 

 are of Triassic age, and the lumps of htematite contained in them 

 were derived from the denuded millstone grit, we can fix the date 

 of the introduction of the iron ore. It must have taken place 

 during the Permian and Bunter Sandstone periods, when this part 

 of the country was dry land, and denudation was wearing down 

 the hills to their present level. 



The Coal Measures were originally deposited on the top of the 

 millstone grit, and then began the series of movements which 

 ended in tilting the whole set of older formations into their present 

 inclined position. The Coal Measures of course went up with the 

 rest, forming the summits of hills of very considerable height ; but 

 denudation set in at once — rain and rivers began the work, and 

 then the land sank beneath the level of the Liassic and Oolitic 

 seas, which helped to complete the ruin of the ancient hills. To 

 account for the haematite in these hills, we need, in the first place, 

 water highly charged with carbonic acid percolating through the 

 rocks, and this is best supplied by rain-water sinking into the hill- 

 sides and running down between the joints ; secondly, this water 

 must pass over beds of carbonate of iron, and this substance is 

 supplied in abundance by the clay ironstones of the Coal Measures, 

 which are a mixture of clay and carbonate of iron, and frequently 

 contain veins of the carbonate. The materials for the Triassic 

 sandstones must have been derived to a great extent from the 

 waste of the Coal Measure hills; and the thickness of the Triassic 

 beds shows that very extensive denudation took place. 



Resuming the whole subject, then, it seems probable that these 

 beds of millstone grit originally contained limestone masses. 



Rain fell on the Coal Measures on the tops of the hills, sank 

 into the ground, becoming charged with carbonic acid, passed over 

 carbonate of iron and became partly charged with it, but still 

 retained enough acid to remove the limestone masses it met in the 

 grit, while at the same time it deposited the iron ore as we now 

 see it. 



The fossils obtained from these beds are reserved for separate 



