E;*+ - Geological Curators

Model 5 - This is the inverted offclat from Model 4, representing a valley side
in horizontal strata.
Model 6 - A simple block model with repeated normal faults offset in one
direction, with rhaded parts to be removed, and the cuts to be glued together.
Model 6a (Fig. 5) - Implicit instructions for first and second cuts with offsets,
interpreted as instructions for making Model VI.
Model 7 - Slight uncertainty about topography, but clearly a minor variant of
Model V with cutting and glueing instructions, and parts to be removed. There
are faint alternative lines for the groups of parallel faults.
Model 7a - A version of 6a (VI) with full surface topography.
Model 8 - The pecked line is the profile of the valley bottom, and, with the
general outline, is the only indication of surface topography.
Model 11 (Fig. 5) - The drawing gives plan and elevation of the faults with the
sequence of cuts and offsets. In the form of a simple rectangular block, faults
1 and 2, lined with white wood, must have been glued before cuts 3 and 4, lined
with dark wood, were made.
Model 12 (Fig. 5) - Although there is no indication on the working drawings, it
is assumed that Model 12 (XII) is a version of Model 11 (XI) with surface
topography.
Model 13 - Simple cutting lines with the valley profile marked by a solid line.
Model 14 - A variant of Model X in which the same group of strata is more steeply
inclined at 450 upstream.
Model 15 - Similar to Model IX, but the succession of strata is inverted, and
dips at 45O.
Model 16 - Second thoughts here with a change from horizontal to gently inclined
(250) strata. Tentative pencil lines could show proposed valley bottom slopes.
Model 17 - Vertical strata, an unmodelled variant of Model 13.
Method of construction
Sopwith (1875, p. ix) was a little misleading in his statement that the
twelve sodels consisted of 579 separate pieces of wood. Twelve slips of wood
representing fault infilling and twenty seven sheets for the strata1 block were P
all that were required. Craftmanship of a very high order was demanded,
however, in jointing the laminae into a solid block, and then band-sawing and
finishing the surfaces with minimum loss of wood. Modelling of topography
into the top surfaces of the blocks was done by eye with only very sketchy
outlines of surface form, or perhaps master copies as a guide.
DISCUSSION
Sopwith simplified the models in 1875 by reducing the number of wood layers,
and issued a revised set of six chosen from the original twelve models of the
1841 set. It is a tribute to him that Lyell (1841), impressed by the usefulness
of the models to the beginner, illustrated three of the models showing V-ing of
strata in valleys, but admitted that the drawings were no substitute for examining
and handling the originals. As an aid to elementary teaching, echoing Sopwith's
insistence that he was writing for the learner in geology, a few surviving
models are still used Tn the Department of Geology of the University of Glasgow
(Rolfe, 1979), and a complete set has been used until recently (Thompson and
Jones, 1979) at Moorland High School, Burslem, Stoke-on-Trent, and at
Southampton University (this issue p.511). Large, eight-inch versions of the
1875 set are also used for public demonstrations in the Geological Museum, South
Kensington (Dunning, 197 8) .
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