This model was designed by William H. Hobbs and published in “An Apparatus for Instruction in Geography and Structural Geology, Scottish Geographical Magazine, December 1908, Figure 8-Model to illustrate the contraction of the crust and the effect of accommodation between layers in the deformation of rocks.”
Hobbs describes the model; “How the process of folding in rocks shortens the crust and distorts or deforms the beds themselves through the accommodation of layers, is forcibly brought home to the class by the simple device illustrated in Fig 8. This model is prepared by sawing from a three-inch plank a strip one inch wide in the form of an unsymmetrical anticlinal fold. Two exactly similar piles of strips of white paper are marked on the long edge with a series of tangent circles provided with vertical and horizontal diameters. . . . On placing now one of the piles of paper in the space cut out from the plank and fastening the two parts of the model together, except within the arch of the folds the circles are changed into ellipses through the accommodation of the sheets of paper just as they would be in rocks through accommodation of the rock laminae.”
This is the same model that appears in the 1908 publication. Some time during the last century it has been taken apart and reassembled with front and back reversed.
Material: wood, paper, steel, ink.