Some of our best-known stones

On this page are links to information about a selection of the better-known erratic stones and groups of stones in our area. Julie Schroder has written about several of these in the Newsletter of the Black Country Geological Society in 2011 followed by articles by Roland Kedge and others in 2011 and 2012. Since then some of these erratics have been better documented. We will continue to research their social history during the project and report our findings.

Roland Rockhound's Boulder Hunt

Here is a list of boulder locations on this page:

1 The Gilbertstone

2 The Warstone

3 The Great Stone, Northfield

4 University of Birmingham, Edgbaston campus

5 Cotteridge Park

6 Masefield Square

7 Woodgate Valley Country Park

8 Frankley

9 Romsley Hill

10 Bromsgrove Cemetery

11 Cannon Hill Park

The map shows how they are spread out in the Bromsgrove and Birmingham districts in relation to our trails.

Map showing location of 11 well-known boulders

The Gilbertstone

Grid Reference: SP 13040 86181

What3 words: signal.match.inform

Roland Kedge at the Gilbertstone
Interpretation board about the Gilbertstone

This stone was used to mark a sharp turn in the Warwickshire-Worcestershire boundary in centuries gone by and gives its name to a whole district near Yardley in east Birmingham. It was moved when a new housing estate was built in 1937 and you can see it now in the grounds of Birmingham City Council’s Blakesley Hall. This is some distance from any of our trail routes.


The Warstone

Grid Reference: SP 05949 87703

What3 words:

The Warstone, Jewellery Quarter, Birmingham

Situated in Birmingham’s Jewellery Quarter in Warstone Lane Cemetery (not on any of our trail routes), the inscription on the slab beneath it reads:

“This felsite boulder was deposited near here by a glacier during the Ice Age, being at one time used as a parish boundary marker. It was known as the Hoarstone of which the modern Warstone is a corruption”

Julie Schroder found that it was at the boundary of the manors of Aston, Birmingham and Handsworth. “Felsite” is a word used to describe a pale-coloured, siliceous igneous rock which in this case contrasts with its dark, weathered surface.

The Great Stone, Northfield

Grid Reference: SP 02503 79381

What3 words: hotels.stays.lines

The Great Stone, Northfield with its plaque

This boulder has the distinction of having a pub and a road named after it. It used to lie inconveniently at the corner of the pub, opposite Northfield Parish Church, but was moved to the nearby 17th century animal pound in 1954. Following a campaign by Roland Kedge, an explanatory plaque was unveiled in a ceremony attended by 100 people on 8th October 2016 at which Dr. Rob Ixer told its geological story.

The Great Stone is at the beginning of our Trail 1.

Aston Webb boulder, University of Birmingham 

Grid Reference: SP 04900 83400

What3 words:

The boulder was photographed soon aftert its discovery at its present location with Professor Charles Lapworth, but the only written evidence we have found is a generalized announcement in the Birmingham Mail on 17th August 1909.

During the Lottery project we researched its geological nature and have presented the results here.  It is unique!



Boulder at University with Aston Webb building behind, early 20th century
Boulder resting on sediment with Professor Lapworth seated next to it
University basalt boulder
Glaciation map from Cotteridge Park plinth

Cotteridge Park

Grid Reference: SP 05061 80194

What3 words: thinks.stick.known

There is a splendid collection of boulders in this park which has been managed by Birmingham City Council since 1911 and by a very active Friends group since threats to its viability in 1997. Louis Barrow, the Chief Engineer of the nearby Bournville Works, and a former student of Charles Lapworth took a great interest and details of the stones’ discovery were published in the Bournville Works Magazine. We studied this site as part of a National Heritage Lottery Fund grant on the history of the park in 2017-18.

The photographs show 1) a reproduction (Bournville Works Magazine, August 1913 p. 263 ) of a map of the Ice Age prepared by Charles Lapworth and mounted on a plinth in the park for many years and 2) conservator Nigel Larkin at one of the boulders

Cotteridge Park lies on trail 2.

Nigel Larkin, conservator, at Cotteridge Park

Masefield Square

Grid Reference: SP 03307 79488

What3 words: king.posed.normal

Outside the community Hall is an impressive cluster of Arenig boulders.  One of them is notable because it is not a volcanic ash like most Arenig boulders, but is an intrusion, that is solidified magma beneath a volcano. This rock has a few larger crystals of white feldspar that formed before the bulk of the material solidified.  The same rock type can be found near Arenig Fawr.

Masefield Square lies on trail 3, which starts in Kings Norton village.

Masefield Square boulders
Crystal tuff boulder

Arenig boulder of an igneous intrusion, (meaning that magma cooled and crystallized underground) with white crystals of feldspar.


Grid Reference: SO 98416 78741

What3 words: desire.sunk.beard

The Frankley area includes several notable sites including a boulder at Balaams Wood exhumed in December 2021 and the two very large boulders shown below next to the old railway cutting at the west end of New Frankley.  Discoveries of boulder clay on Frankley Hill in the late 19th century consolidated ideas about the glacial theory.

Trail 5 is a walk from New Frankley into the surrounding countryside, but we are also planning a geological time line along the route of the old Longbridge-Halesowen railway line.

Large boulders next to the railway cutting at Frankley

Woodgate Valley

Country Park

Grid Reference: SO 99585 83331

What3 words: overnight.notion.dress

Birmingham City Council have invested in improvements to the path network in this ‘green lung’ flanking the Bournbrook and which contains a riding stable. In this project four boulders were exhumed or repositioned in December 2021 so that the public can see them. One photograph shows a boulder which started off as a volcanic ash containing hand-sized pieces of rock thrown out of the volcano.  These are now weathered out as holes. The other photo shows a boulder exhumed by contractors. Subsequent cleaning in February 2022 has brought out the volcanic structure very clearly.

Woodgate Valley and nearby Quinton is the site of walking trail 4, much of which is accessible for those with mobility impairments. There are plans for an exhibition in the Visitor Centre including 3-D prints of a less accessible quartz boulder in nearby Broadhidley Wood

Exhumed boulder at Woodgate Valley Country Park

Romsley Hill

Grid Reference: SO 96247 78868

What3 words: stuff.soaks.worked

The view from Romsley Hill takes in much of Birmingham and the Black Country and several boulders are mounted on the village green. The largest two (pictured) are basalt from nearby Rowley Regis which were likely transported by people (to be confirmed), but the other derives from Arenig and basalt erratics have been found on nearby Frankley Hill. Late 19th century geologists realized that finding glacial deposits so high up meant they had to be deposited under land ice rather than from floating icebergs.

Romsley Hill lies on cycling trail 6, but can also be reached on foot from Frankley, or by car.

Basalt bouldres from Rowley Regis at Romsley Hill

Bromsgrove cemetery

Grid Reference: SO 95657 70784

What3 words:

Two boulders flank the entrance to Bromsgrove cemetery where there is an explanatory notice reproduced here.  Although it was reported in the late 19th century that there were 90 boulders in the Bromsgrove District, the Presidential Address of the Bromsgrove Institute by Humphrey (1903) bemoaned the loss of boulders in the preceding decade.

Explanatory board about the boulders outside Bromsgrove cemetery
Bromsgrove cemetery with boulders either side of the entrance

Cannon Hill Park

Grid Reference: SP 06560 83715

What3 words:

A boulder was retrieved when the lake was excavated in 1873 and provided with a protective railing at first as in the photograph  from a publication by Harrison in 1898. A smaller boulder is visible in the photo which is now lost. A new meshwork surrounding was installed in December 2021.

Cannon Hill Park is a popular meeting place and one of seven new interpretation boards will be placed here in 2022, this one funded by the Quaternary Research Association.  The park lies on (cycle) trail 7 and can be reached on foot from Birmingham University at the end of trail 1. It is readily accessible by public transport.

Cannon Hill Park boulder with railing
Boulder at Cannon Hill Park