The Erratic Boulder Hunt
Where should we look?
Here are some ideas….
1. In parks and public spaces
2. In gardens
3. Along the edge of fields
4. In banks and beds of streams
5. Hidden in dense vegetation
6. besides roads or publicly accessible railway excavations
7. On roadside verges
8. Hidden in walls or buildings
9. Used to mark estate or district boundaries
10. In churchyards
11. Parked beside trees
Here is a rockhound’s treasure map made by Fred Martin in 1890!
Martin’s map of 1890 shows us that the Bromsgrove area is a good place to hunt for boulders, but also in a wide arc from the edge of the Clent Hills through Frankley, and Northfield to Harborne.
This information is plotted on a modern road map further down this page.
The arc in the Northfield areamay represent an “end moraine” – the place where the snout of the glacier paused before retreating. During the pause, the forward movement of ice, would have been balanced by melting of ice, leading to an accumulation of boulders.The lower half of this photograph shows a modern curved end moraine (Tsanfleuron, Switzerland).
Ice came from the right in the year 1855 and stayed until 1860 before retreating. Since then a stream has eroded through it. Many boulders can be seen on the surface of the moraine.
In order to help your search in the SW Birmingham and Bromsgrove area, the points from the 1890 map have been replotted onto a modern road map. Remember – only boulders on public land should be investigated. Our project concerns the boulders from Arenig and those locally derived basalt (from Rowley Regis) and Coal Measures sandstone which were deposited in one or more ancient ice ages. The Black Country area to the north-west has boulders from Criffel and Eskdale which were deposited in the last ice age. You can find a link to a map of the whole West Midlands here.
The base maps contain OS data © Crown Copyright [and database right] (2022)