168 Burton: The Cleveland Ironstone. 
and west was, at this period of geological history, dry land, 
and probably rising, creating a slope to the east, which is 
exactly the condition necessary for the formation of the Lias 
deposits of Yorkshire. It was also the area, as was that of the 
South West of Scotland, where the greatest disturbance was 
going on and seismic and plutonic forces were most active. 
So that in the region from which the streams probably ran 
were those physical features, natural forces and lithological 
conditions necessary to explain the source of the mineral 
constituents of the Cleveland Ironstone. 
It must, however, be conceded that for a full explanation 
of the whole series it is necessary to assume that deposition 
was not continuous, but intermittent or interrupted, and that 
there were many alterations in‘land and sea level, but I think 
we are fully justified in reasoning from effect back to cause, 
and in saying that such oscillations of land and sea level did 
take place during the whole of that period. The same action 
must have been repeated time after time.* 
(Zp be continued). 
oo 
‘How birds make love,’ is the title of an article in Part 27 of Cassell’s 
Nature Book, by Mr. Oxley Grabham. 
Mr. J. Arkle refers to the forms of Cenonympha in various northern 
counties in The Exitomologist for March. 
In The Scottish Naturalist for March, Mr. W. Eagle Clarke describes 
A New Racial Form of Song-thrush from the Outer Hebrides, with the 
name Turdus musicus hebridensis. 
On the strength of specimens found at Radclitfe-on-Trent by Professor 
Carr, Mr. K. J. Morton, in The Entomologist for March, writes on ‘ An 
Addition to the List of British Plecoptera: Reinstatement of Chloroperla 
venosa. 
In a note on ‘ The Origin of Septarian Structure,’ by Dr. A. M. Davies 
in The Geological Magazine for March, he refers to the fact that this 
structure is due to evpanszon of the nodules, and not to contraction as is 
usually supposed. 
From an article by the curator, Mr. F. Williamson, in The Museums 
Journal for March, we learn that ‘ Rochdale now possesses an Art Gallery 
and Museum which compares very favourably with those of many much 
larger towns and cities.’ 
The Museums Journal announces the death of Robert Cameron, who 
was for many years honorary curator of the Sunderland Museum, and 
‘was in advance of his time in the broad views he took of the potential 
value of museums in the general scheme of education.’ He was in his 
eighty-eighth year. 
* The question arises, was the iron in the interbedded shales, or in 
the Estuarines of the Upper Lias and Inferior Oolite ? [ think in the 
interbedded shale, as there is not much evidence of leaching in the Upper 
Lias, and the iron and the limestone does not shew that diminishing ratio 
of iron to lime in the lower beds that one might expect if it had to pass 
through and leave some of it in the upper beds. 
, Naturalist, 
