The concept of the time trail “From Fire to Ice” is to explore Deep (geological) Time by walking the trail which runs along or close to the railway line (now cycle and walkway) through New Frankley.

The glacial erratic boulders that are the subject of Trail 5a bookend the Fire and Ice Trail.

It starts in Balaams Wood where there are two boulders, one by the pathside and one in a tree root which formed as a result of explosive volcanic eruptions about 450 million years ago in the Ordovician Period in what is now Wales.  At that time, England and Wales were in the southern hemisphere.

Walking westwards is like moving forward in time during which England gradually drifted up to the equator.  We go through the Silurian Period (there are famous fossils from Dudley) through the Old Red Sandstone to the Carboniferous which locally  is represented by Coal Measures.  Then through the deserts of the Permian and rivers of the Triassic with its land dinosaurs to the warm tropical seas of the Jurassic and Cretaceous with their aquatic dinosaurs.

Eventually the climate started to cool as England drifted further north and the Ice Age arrived. During at least one severe Ice Age, boulders of rock from North Wales were brought to Frankley and two excellent examples are above the old railway cutting at the west end of New Frankley.