134 Analyses of Books. [August, 



Rev. J. Hailstone, F.R.S. F.L.S. Woodwardian Professor in 

 the University of Cambridge. 



The upland parts of Cambridgeshire consist of chalk hills, 

 which, at their northern extremity, appear to rest on an extensive 

 bed of blue clay, provincially called gault ; and on the east, on 

 the borders of Suffolk and Essex, the chalk is covered by a thick 

 deposit of clay. The grey or lower chalk is the most abundant 

 in Cambridgeshire, where it is distinguished by the name of 

 clunch. When burned, it affords a lime in very high esteem, 

 and the harder beds form a good building stone, which, from 

 its standing the fire well, is in great request for the backs of 

 grates and similar purposes. The clunch and subjacent gault 

 appear to pass into each other by insensible degrees ; the clunch 

 first becomes sandy, then assumes the appearance of an argilla- 

 ceous loam, and as it approaches nearer to the gault, becomes 

 mixed with green sand, and contains imbedded nodules of a 

 ferruginous indurated marl. The mass then becomes more uni- 

 form in structure, and at length is not to be distinguished from 

 the blue argillaceous marl which forms most of the beds of 

 gault. 



III. — 7. Some Observations on a Bed of Trap, occurring in the 

 Colliery of Birch Hill, near Walsall, in Staffordshire. By 

 Arthur Aikin, Sec. G. S. 



The following are the circumstances described in this paper. 

 A vertical dyke of Trap intersects part of the colliery at Birch 

 Hill, and comes up to the surface, forming a long, low mound 

 from 70 to 100 yards broad, and known by the name of the 

 green rock fault. A wedge-shaped lateral prolongation of this 

 trap has apparently intruded itself between two of the coal 

 strata, which in those parts of the colliery where the trap does 

 not occur are found in contact with each other. The bed which 

 covers the trap is shale, containing subordinate beds of iron- 

 stone, and presents no peculiar appearances, but the three beds 

 which he below the trap, namely, sandstone, shale, and coal, of 

 the aggregate thickness of about 7 4. feet, differ remarkably from 

 the same beds where they are not covered by trap. The sand- 

 stone is broken, and angular pieces of the shale are imbedded in 

 it ; the structure of the sandstone is more compact ; it is harder 

 and of greater specific gravity. The shale is much indurated, 

 has a glossy metallic lustre, and is destitute of bitumen . The 

 coal has a shining, somewhat iridescent lustre, is entirely desti- 

 tute of bitumen, and when put in the fire, burns rapidly, like 

 common cinder ; but where the coal is not covered by the trap, 

 it exhibits the usual characters of common bituminous stone 

 coal. 



III. — 8. A Geological Description of Glen Tilt. By J. 

 M'Culloch, M.D. F.L.S. Pres. G. S. &c. 



The interesting appearances in Glen Tilt, first we believe 

 observed by the late Dr. Hutton, have long afforded materials 



