780 é, REPORT—1863. 
In 1857 Mr. Howse proposed the following division of the Magnesian 
limestone, which has been adopted by Mr. Kirkby, by Professor Geinitz, of 
Dresden, and also by Professor King more recently :— 
ENnGLIsH SERIES. GERMAN EQUIVALENTS. 
Magnesian Limestone. Zechstein. 
1, Upper Group .j«.. a. Upper yellow-limestone. a. Plattendolomit, and 
b. Botryoidal do. b. Kugelkalk, &e. 
2. Middle Group .... ¢. Cellular, and c. Rauchwacke. 
d. Shell-limestone. d. Dolomit, Asche, &c. 
3. Lower Group .... e. Compact limestone, and a Zachatern 
Ff. Conglomerate. 
Doubtless, any one examining these rocks, by commencing at their outcrop 
near South Shields, which is the usual starting-point, and going southward 
along the coast, would readily recognize these groups. The line of separa- 
tion between the compact and cellular rocks is clearly distinct, as is also the 
first appearance of the botryoidal rocks, south of Marsden. But there are 
equally well-defined changes in the character of the rocks at other points 
along the coast (as at the point near the blast-furnace south of Seaham Har- 
bour) which have not been made use of for grouping the Magnesian limestone 
into distinct series of beds; and there are also, south of Seaham, several 
other groups of shell rocks with distinct and variously-marked differences of 
lithological character. It is not at all to be wondered at that these points of 
strongly-marked difference of lithological character, and apparent non-con- 
formability of deposition, should occur throughout such an extensive deposit 
as the Magnesian limestone. These occur constantly to a far greater extent 
throughout the Coal-measures, and yet it would be extremely hazardous to 
venture on any speculative subdivision of those rocks *; most probably all 
the variations of lithological structure, running through all the stages of fri- 
able, earthy, rubbly, starry, marly, crystalline, botryoidal, coralloidal, sphe- 
roidal, mammillated, brecciated and pseudo-brecciated, soft-laminated and 
hard-laminated, conglomerate, conglobate, concretionary, oolitic, and honey- 
comb, are simply due to the effects of local action at the time of deposition— 
rocks of the same stratigraphical position taking alternately any or all of the 
above lithological types. 
On the Manufacture of Iron in connexion with the Northumberland 
and Durham Coal-field. By Isaac Lowrn1an Brin, Mayor of 
Newcastle. : 
Ture is probably no district, where the manufacture of iron is carried on, 
which presents more features of interest, and embraces within its range 
greater variety, than that which is worked in connexion with the coal-field 
of Northumberland and Durham. Notwithstanding this, the iron metallurgy 
of the North, which it will be the province of this paper to explain, owes 
none of its importance to the existence of any of the ores of iron in 
those measures which belong more immediately to the coal-formation. In 
* The roof of a seam of coal consists at one place of a hard sandstone, which, thinning 
. 
Scotland, Staffordshire, and South Wales, the shales of the coal-measures — 
¢ 
a 
=) 
a 
out more or less abruptly, is replaced by soft shale, and-at times the shale comes in asa 
wedge, without displacing the sandstone, and gradually increases to a thick bed. Even 
beds of coal themselves, commencing with a few inches, thicken to many feet, are sepa- 
rated by layers of shale into distinct seams, and again become one by the disappearance — 
of the band of shale. : 
