O74 Correspondence—A. R. Horwood. 
2. ‘‘ Jurassic Plants from the Marske Quarry.”’ By the Rey. George 
John Lane, F.G.S. 
The Marske Quarry is situated on the northern side of the Upleatham 
outlier in the Cleveland district of Yorkshire. It is about 500 feet 
above sea-level. In the quarry several varieties of rock are exposed, 
namely shales, small coal-seams, sandstones, and a ferruginous bed. 
The beds are of Lower Oolite age, and belong to the Lower Estuarine 
Series. As the Millepore Bed is absent in the district, the Lower 
Estuarines and the Middle Estuarines may be one continuous deposit. 
From this quarry Dictyozamites was recorded for the first time in 
England, its occurrence being made the subject of a paper presented 
by Professor Seward to the Geological Society in 1903. The writer 
has obtained nearly forty species from the quarry, among which are 
many characteristic Wealden plants. This discovery is most interesting, 
especially when one considers the vast interval of time that elapsed — 
between the horizons of the Inferior Oolite and the Wealden. 
CORRESPON DEN CHE. 
THE ORIGIN OF THE BRITISH TRIAS. 
Sir,—In reply to your correspondent Mr. W. B. Wright,! of the 
Scottish Geological Survey, who has doubtless heard much of the 
Desert theory from his former colleague, Mr. T. O. Bosworth (who has 
so ably described the evidences of desert conditions in Leicestershire), 
Mr. Wright must know that it is unusual to criticize an abstract ? 
before the full text of the paper is printed. I shall therefore be 
as brief in my reply as I was in the abstract, only quoting the 
numbered passages from Mr. Wright’s letter. I may reply— 
(3) Ido not speak of a general absence of delta-bedding, for see (9). 
It does occur. Professor Bonney is cited by me as proving the delta 
origin of the Bunter, and I do not propose here to add one iota to his 
evidence. It is quite clear enough, and the Survey Library contains 
the papers in which Professor Bonney published his proofs. The 
dactyloid form is just a further point of analogy, and the extension 
of the Trias delta-head is suggested by evidence from deep borings 
(as to which let Mr. Wright ask Mr. Whitaker, who will also give 
him ‘all the bibliographical assistance he needs, as he kindly did 
for me) in the East and South-East of England, chiefly made in 
connexion with explorations for coal. 
(9) It would be equally as fruitless as trying to find the river-bed 
of the Triassic delta (or its tributaries) to expect to show beds in 
the act of tilting through an angle of 45°; but it is an axiom of 
modern physical geography (which I merely extend to the past) that 
beds when subsiding do tend, when so elevated, to become horizontal 
finally. The discontinuity of delta-bedding, laterally and vertically, 
seen so clearly in Staffordshire and Notts., is an ocular demonstration 
of what has happened in the past; but no more is to be expected. 
The characteristic overlapping, of which Mr. Wright must have 
1 See Grou. Mac. for November, 1910, p. 526. 
* See ‘‘ Origin of the British Trias’’, by A. R. Horwood (Abstract of paper 
read at the British Association, Sheffield, September, 1910): Gzox. Maa., October, 
1910, p. 460. 
