228 



THE GEOLOGIST. 



exhume the relics of its once teeming population from their stony 

 tomb. If, however, the geologist has this advantage over the naturalist, 

 he has often only the skeletons, or, indeed, but mere imperfect 

 remnants by which to decipher and restore the forms and attributes 

 of ancient creatures ; while the naturalist, though he cannot walk 

 beneath the waves, still can, by the aid of the dredge, collect the 

 animals in their full symmetry and beauty. The student of the pre- 

 adamitic earth has, however, a no less delightful task, and the very 

 labour and the difficulty of the restorations bring their own reward, in 

 making known to others the marvellous works of God in the earliest 

 ages. In this spirit let us review the history of the Lias, and it shall 

 tell its OT^n story as we proceed. 



The Lias has a very extensive range in Gloucestershire, and consists, 

 for the most part, of alternating beds of clays, limestones, and shales, and 

 towards the middle includes a thick and important mass of sandstone. 

 Lithologically it presents a very different aspect from the Oolites above 

 it, as the student cannot fail to observe. It contains a great 

 abundance and variety of organic remains, the greater part of which 

 are peculiar, some being limited to particular zones (especially the 

 Ammonites), and others occurring indiscriminately throughout the 

 formation, which presents, as a whole, a great uniformity of structure 

 and details, and consequently can be most readily recognised in different 

 and distant localities, even without the aid of characteristic fossils. In 

 general, no cautious geologist would venture to determine a rock by 

 mere similarity of lithological character, the only safe rule to distinguish 

 the same formation in another country being by its relative position 

 with regard to other superior or inferior rocks, and its organic remains. 

 The Lias is essentially a muddy deposit, and from the regular layers of 

 which it is made up, and which may be seen even in a small section, the 

 term Lias appears to have been derived. In Gloucestershire, it is 

 divided into upper, middle, and lower, distinguishable from each other 

 by their order of superposition and their peculiar fossils. The upper and 

 middle divisions form the base of the Cotswold Hills, and their 

 detached outliers; while the lower division, here and there^^constituting 

 lesser elevations, for the most part spreads over the vales of Gloucester 

 and Berkeley, and occupies the whole of the comparatively level tract 

 between tlic Cotswold Hills on the east and the Hed llarl on the west, 

 its narrowest point being the more central region in the neighbourhood 



