148 COAL AND COAL-FORMATIONS. 



soft, Ml of water, and easily cut ; and when brought to 

 the surface, dry and break up, and soon crumble down 

 under the influence of the weather. They are also less 

 regular in their bedding than the older coals thickening 

 and thinning capriciously; but in some instances their 

 bedding is regular and continuous over considerable areas, 

 and their quality is so much improved that they are scarcely 

 distinguishable from ordinary coal. One remarkable in- 

 stance of this kind, the Zsil valley in Transylvania, was 

 visited in 1862 by Professor Ansted, who found not lig- 

 nite, but coal differing little from some varieties of English 

 coal, lying in regular beds of great thickness, and alternat- 

 ing with shales, ironstones, and grits. Of course, all the 

 vegetable accumulations of the Tertiary system are not 

 precisely of the same age, nor have they been deposited 

 under the same conditions, and thus we may expect to find 

 differences among them, just as among the coals of the older 

 formations. And hence it happens that some of these 

 lignites are scarcely fit for pottery or brick-kiln purposes, 

 while others (certain compact and lustrous varieties) are 

 advantageously used for locomotive engines and for metal- 

 lurgical operations. 



Although seams of lignite are occasionally found in the 

 Cretaceous and Oolitic systems, yet, generally speaking, the 

 Secondary strata the Chalks, Oolites, and New Eed Sand- 

 stones are characterised by the presence of true coals. 

 The seams may not be continuous over extensive areas 

 that is, may thicken and thin somewhat capriciously but 

 still mineralisation of the mass is complete, and we are 

 presented with bituminous coals of varying commercial 

 value. Such Secondary coal-fields occur at Brora and 

 Whitby in Britain ; at Fiinf kirchen and Oravicza in Aus- 

 tria; at Burdwan, Nerbudda, and other districts in In- 



