C. Stephen Briggs (2009)
The routes shown for Shap granite erratic transport are themselves somewhat erratic, and will have been much more erratic than shown -- but the main point of interest is the final resting place. One Shap granite erratic (at least) is shown as having been dumped in the Severn estuary. So here is an interesting question: could the "granite debris" found at West Kennet be related in some way?
The Shap granite, a distinctive coarse-grained granite with large pink orthoclase feldspar, was intruded late in the Caledonian orogeny around 394 million years ago. The granite had a complex evolution involving multi-stage addition of basaltic magma to the magma chamber and assimilation of country rock. Much of the magmatic history is recorded in the compositional variations of the feldspar megacrysts. This rock has been widely used as a decorative building stone
In their analysis of the granite "grus" at West Kennet Ixer, Bevins and Pirrie decide that it has probably come from Cheviot -- maybe from Cunyan Crags. This is well to the east of Shap.The West Kennet grus: how far?
by Rob Ixer, Richard Bevins and Duncan Pirrie
British Archaeology, March/April 2022, pp 39-41