07/07/2026
The place known as Chimney Gulch between Shoe Cove and Flatrock boasts beautiful folds and related faults that form part of a fold and thrust belt. They represent a style of tectonic deformation known as “thin skin deformation” with basal decollements (low angle reverse fault) being good indicators. Deformation is confined to the sedimentary sequence around the slip plane and is “rootless”, it does not extend deep into the Earth’s crust. In this style of deformation, repeated sections of the same rock are seen over and over as thrust faults, coming up from the decollement, stack the same layer on top of itself.
Deformation here is attributed to the Avalonian orogeny, a major late Neoproterozoic mountain-building event (~650 to 540 million years ago) driven by the subduction of oceanic crust beneath the active peripheral margin of the supercontinent Gondwana. Fragments of this ancient belt are now scattered across the North Atlantic, southeastern New England, England, Wales, and parts of northwestern Europe.
