E;*+ - Geological Curators

It is evident that three-inch lengths were sawn off the laminated block
and then sawn either along the junction of Beds 11 and 12 or Beds 12 and 13 to
give the blocks from which models involving horizontal strata were made.
Five models with inclined or vertical strata were sawn, as shown onthedrawing,
from the offcut block, leaving an intriguing s1,ab of the, complete sandwich,
half an inch thick.
Instructions for Models 1 to 8 are reasonably explicit; there are no
sawing diagrams for Models 9, 11 and 12, and the drawing for Model 10 is, to
say the least, enigmatic. Of particular interest are the clear indications
that Sopwith was developing his ideas on how the models should appear: roughly
shaded areas have to be removed; the outline of Model 3 is changed; cutting
instructions of Model 4 have three variations in pencil; the whole concept of
Model 16 is changed by reorientating the base of the model; cuts representing
faults have to be glued; certain offcuts are marked 'keep'.
Where the cuts for faults are obliquely across the block, the simple
elevations in Fig. 3 are an insufficient guide. Cutting sequences, cut
directions and inclinations and offsets for Models 11 and 12 are given on the
back of the drawing (Fig. 5). There is clearly some confusion over Models 6
and 7 which are renumbered 9 and 10 on the reverse side of the drawing, with
intersecting rather than parallel cuts along the faults.
Of particular interest are the clear indications (Fig. 5) that the outlines
of several of the drawings have been pricked through, presumably to transfer
the outlines to the laminated wood block.
Twenty-two different models can be accounted for, including only one
specific ex-ample (Model IV) in slightly inclined faulted strata. This does
not include Model 10 outlined on Fig. 3., in which three solid cut lines are
indicated. The upper line is reminiscent of the surface topography in Model
11, 'Coal Strata near Newcastle on Tyne' with the normal horizontal Lower
Carboniferous sequence rather than the gently inclined coal measures succession
in Model I1 (Sopwith, 1841, p. 28). The two lower lines could represent a
modelled valley cut into horizontal strata, similar to Model Ia of the 1841
set.
The succession of strata shown in the drawings
On the working drawings, twenty seven different beds are numbered and
colour-coded and the succession is the same as that in the 1841 illustrations
of the models. A complete succession can be built up from the drawings of
Models I, V11 and X (Fig. 6), and from this and the colour coding on the original
working drawings (Figs. 3, 4) the lithological succession can be inferred.
Sopwith, in his description of Model I, identifies Bed 2 of the warking drawing
as Pattinson's sill, Bed 4 as the Little Limestone, Bed 10 as-the Great Limestone,
Bed 11 as the tuft, and describes the lithology of Beds 1, 7, 12. The Four
fathom Limestone, mentioned in the account of Model, IV is Bed 18. Bed 23 is
therefore the Three yards Limestone, and Bed 27 the Five-yard Limestone - the
lowest limestone reached by mining operations in East Allendale (Dunham, 1949,
p. 20) .
The inferred succession has been compared with that given by Forster
(1821, p. 167-168), and cross-correlations between this source, the working
drawings and the 1841 descriptions are given in Table 2.
The succession of strata from the Nattrass Gill Hazle up to the Girdle Beds
above Pattinson's Sill is also published on 'The Plan of Holyfield Lead Mine'
(Sopwith 1829). From the various descriptions of the strata available, the
'ithology of the beds coloured light purple, Beds 1, 12 and 19, ean be determined.