58 Sir H. H. Howorth — Destruction of the Chalk. 



attenuation of these beds between Stratford and Burford, places 

 lying 26 miles apart, on a line running due N. and S. As we 

 have seen that the maximum attenuation takes place along a line 

 running N.W. and S.E., by drawing a line at right angles to this 

 {i.e., N.E. and S.W.) through Stratford, and letting fall a per- 

 pendicular from a point represented by Burford, we find the length 

 of this perpendicular to be about 22 miles, which represents the 

 distance through which the Upper Keuper Marls have thinned out 

 from about 640 feet to 291 feet. This gives about 16 feet per mile 

 as the true rate of attenuation between Stratford-on-Avon and 

 Burford. Mr. De Bance, by the use of Brofessor Hull's data, 

 arrives at the conclusion that between the Liverpool district and 

 Warwick the Upper Keuper thins out at an average rate of 23 feet 

 per mile, a rate which we see is not maintained as we get further 

 south. 



The Stratford boring unfortunately does not give us the thickness 

 of the Lower Keuper, but as this subdivision of the Trias was 

 penetrated to a depth of exactly 200 feet and still maintained the 

 same characters, I think it probable that it is at least 300 feet 

 thick and perhaps more. It is at any rate of greater thickness than 

 the Lower Keuper of Warwickshire, where according to Brofessor 

 Hull it is represented only by 150 feet of rocks. This discrepancy 

 is probably due to the local thinning out of the coarser sediment 

 against the older rocks of the Warwickshire Coalfield. We have 

 a good example of such a local attenuation of the Trias on the 

 north-west side of the Leicestershire and South Derbyshire Coalfield 

 just East of Burton-on -Trent, .where the Keuper thins out against 

 the Carboniferous Bocks, which here formed an old coast line in 

 early Triassic times. 



III. — The Destruction and Shattering of the Chalk of 

 Eastern England. 



By Sir Henry H. Howorth, K.C.I.E., M.P., F.E.S., F.G.S. 



ASHOBT time ago I read a paper before the Geological Society, 

 of which an abstract appeared in the Broceedings, in which 

 I discussed some questions of critical interest in the geology of East 

 Anglia. 



I am more than pleased to find that some of the conclusions 

 I pressed, and which I had long ago reached, have been discussed 

 by two such excellent geologists as Brofessor G. A. Cole and the 

 Bev. E. Hill, whose papers were printed in the December Number 

 of this Magazine (pp. 553 and 555). 



That the Chalk of Eastern England was originally laid down in 

 horizontal beds no one will, I presume, deny. That since it was so 

 laid down it has been folded and bent into vast curves, no one 

 who has studied either the surface contours or the well-borings 

 will venture to question. That this folding of the Chalk into 

 a series of wolds with intervening valleys must necessarily, unless 

 the Chalk could slip over its lower beds, have been accompanied 



