The Erratic Boulder Hunt: Introduction
Calling all rockhounds!
In 2022 we are designing and rolling out boulder trails in the SW Birmingham and Bromsgrove districts. We want to make the most of the boulders that can be seen, but we don’t know what happened to many of the 19th century finds.
Can you help?
What to do
If you live in SW Birmingham or the Bromsgrove District, look around your local area for large stones and send in a picture to our Facebook page, or to our email address if you are not on Facebook. Show us a screen grab of a map or use what three words to say where it is. Details below.
Boulders on public land that we already know about are shown on the map at this link.
The 19th century was a great era of discovery, including the new idea of an ice age. Prime evidence of this was the presence of large blocks of distinctive types of rock transported long distances from their source. Although some people thought they had floated in on icebergs in a Great Flood, it was soon realized they were transported by glaciers flowing over the land. Before 20th century urbanization, few of these boulders had been moved by people. The position of the boulders could therefore be used to map out the ice movement. They are called erratics.
In Staffordshire and Wolverhampton the erratic blocks matched granites from the Lake District and Scotland. Strangely, these are absent in Birmingham and Bromsgrove: instead were found boulders of volcanic rocks from Wales. Hundreds were documented, but even by 1901 an author was bemoaning their disappearance by burial or breakage.
Here is part of a map by Fred Martin in 1890 showing the distribution of Welsh erratic boulders (squares) and locally derived boulders, mostly from Rowley Regis (circles).
We have rediscovered dozens of these stones, but only a few are labelled on site to say what they are. Nowadays developers often place large stones from quarries as a feature. Attractive though they are, they don’t have the same heritage value as erratics. We want to document the natural heritage before it is completely diluted by all the stones imported by people.
Martin’s 1890 map of erratic boulders
What to do
If you live in SW Birmingham or the Bromsgrove District, look around your local area for large stones and send in a picture to our Facebook page, or to our email address (firstname.lastname@example.org) if you are not on Facebook.
Show us a screen grab of a map or use what three words to say where it is.
In this way, we can all share and comment on the discoveries. Geologists in our team will feed back on what we think the boulders are and may ask for additional close-up photos. In some cases, we may be able to meet you at the site to find out more. Here is a map where you can zoom in and click on a site to see a photo of each boulder that we know about together with a brief description.
We have prepared several web pages to help you (see menu at top of page):
What do the erratic boulders look like?
How do we know where the boulders came from?
Where should we look?
Some of our best stones
The Ice Ages