The Worcester Geogarden

The Geogarden is situated on the St John’s campus of the University of Worcester It is a unique piece of construction and compact landscaping which displays rocks from Worcestershire and the surrounding area. These rocks cover nearly 700 million years of Earth History and tell a fascinating story of continental collisions, shallow tropical seas, coastal lagoons and swamps, hot deserts, vast ice sheets and polar deserts. The garden was completed in 2016

The Rocks

Most, but not all, of the important landscape-forming rocks of the surrounding district are displayed in the Geogarden as large boulders set in a series of ‘beds’ which are lined by pebbles. However, for many of the ‘softer’ rocks in the area, suitable exposures which might have provided stones of sufficient size for the garden, have not been readily available. In the case of the oldest rocks on display, that is, those from the Precambrian Malverns Complex (up to 677 million years old) , they were obtained, with permission from the Malvern Hills Trust and the AONB, from the smaller boulders lying around in various old quarries on the Hills. A cairn was constructed in the garden to display these examples of igneous and metamorphic rocks (bed 1). At the other end of the geological timescale, the cobbles and pebbles in all the other beds in the garden were deposited less than 0.5 million years ago in the latter part of the Quaternary period, and were obtained from active gravel workings.

Plan of the Geogarden, located on the St John’s campus of Worcester University. The circled numbers refer to the individual rock ‘beds’ described below. The ‘You are here’ signs indictate the location of two large interpretative boards.

The following is a condensed description of the rocks contained in each of the beds. Much fuller information can be found in the app, about which further details are given below. There is also a takeaway leaflet available on site.

Note that the listing below is in chronological order, and not in a continuous walking sequence. However, all the beds are within a few metres of each other. Discover your own best way!

The Cairn: Malverns Complex

Age: Precambrian (677 million years)
Rock Type: Igneous (diorites and granites)
Formed: The Malvern Complex represents some of the oldest rocks in England. They were formed within a magma chamber above a subduction zone within a mature volcanic arc.
Continental Position: 60^o south of the equator.
From: Malvern Hills, Herefordshire and Worcestershire

Mountsorrel Granodiorite (Caradoc Formation)

Age: Ordovician (450 million years)
Rock Type: Igneous, granodiorite
Formed: They were formed within a magma chamber above a subduction zone within an immature island arc..
Continental Position: 30^o south of the equator.
From: Mount Sorrel Quarry, Charnwood district of Leicestershire.
Donated by: Lafarge Tarmac

Much Wenlock Limestone Formation

Age: Silurian (420 million years)
Rock Type: Sedimentary, Limestone
Formed: Formed in a huge coral reef. that stretched from the Welsh borders to the east of the Malvern Hills. The limestones contain the broken remains of ancient reef-dwelling creatures.
Continental Position: 25^o south of the equator.
From: Lea Quarry, Much Wenlock, Shropshire.
Donated by: Edge Renewables

Forest of Dean Stone, Pennant Sandstone

Age: Carboniferous (310 million years)
Rock Type: Sedimentary, sandstone
Formed: The Pennant Sandstones were formed by large rivers flowing northwards across a delta or a swampy environment..
Continental Position: Close to the equator.
From: Bixslade Quarry, Forest of Dean.
Donated by: Forest of Dean Stone Firms

Fossil from Pennant Sandstone Formation

The large slab of Pennant Sandstone forming the centre piece of the Geogarden contains the fossil impression of the trunk and leaf from a giant tree fern called a Lepdodendron, which thrived during the Carboniferous period

Halesowen Formation and Bromsgrove Sandstone Formation

Thomas Telford’s design for the Bewdley Bridge was built in 1798. The main part of the bridge is constructed from pale, buff Bromsgrove sandstone. The greenish grey Halesowen Formation was used for the balustrades. These rocks were retrieved when the bridge was repaired in 2010.

1. Halesowen Formation

Age: Carboniferous (308 million years)
Rock Type: Sedimentary, sandstone
Formed: Flood or terrace deposits formed next to fast flowing river channels..
Continental Position: 30^o south of the equator.
Age: Carboniferous (308 million years)

2. Bromsgrove sandstone Formation

Age: Triassic (245 million years)
Rock Type: Sedimentary, Sandstone
Formed: By rivers flowing over a desert environment
Continental Position: 20^o north of the Equator.

Dolerite: (olivine micro-gabbro)

Age: Carboniferous Period (307 million years)

Rock Type: Igneous

Formed: Formed as a result of tectonic activity during late carboniferous period. Stretching of the Earth’s crust formed faults or fissures which allowed molten rock or magma to rise. The magma was pushed between the layers of rock where it eventually cooled to form a horizontal sheet of rock called a sill.

Continental Position: Close to the equator.

From: Titterstone Clee, Shropshire.

Donated by: Midlands Quarry Products

Worcester Building Stones Bed

Stone Numbers 1,2: Salop Formation

Age: Carboniferous  (307-309 million years)

Rock Type: Sedimentary, sandstone

Formed: The reddish sandstone (1) was retrieved from the site of the Hive in Worcester City centre. The greyish green blocks of sandstone (2), including the one with the mason’s mark and tile repair was used for the Saxon parts of Worcester Cathedral including the chapter house and nave arcade piers.

Stone Numbers 3, 4: Bromsgrove Sandstone Formation

Age: Triassic (245 million years)

Rock Type: `Sedimentary. sandstone

From: the red sandstone is from 17th century parts of Edgar Tower, Worcester Cathedral (3). The pale orange sandstones were found during construction of the Hive (4).

See annotated image.

Cotswold Stone (Norton Limestone Formation)

Age: Jurassic  (165 million years)

Rock Type: Sedimentary, oolitic limestone

Formed: The rocks are comprised of small, rounded pellets called ooliths that have been buried and cemented together to form limestones. The ooliths were formed in clear, shallow, sub-topical seas in an environment similar to the Bahamas today,

Continental Position: 30^o north of the equator.

From: Rollright Quarry, Nr. Chipping Norton, Oxfordshire

The  Geogarden app

A splendid app has been devised by Mike Brooks (one of the Trustees of EHT) to accompany the Geogarden. You can use this app to whet your appetite by previewing the garden, or better still, to use it as your guide when you walk around. The app is easy to navigate, profusely illustrated, and full of information about the environment in which each of the rock types were formed, and when and where they were formed. There is a choice of three levels to accommodate different background knowledge: young geologist, curious visitor, or geologist.

The app is available for free on the  Apple App Store for all iPhones and iPads and Google Play for android phones and tablets.

How to visit

The garden is set amongst amongst the academic buildings of the University campus at St John’s in Worcester.  If you are visiting as an individual, then you should call in at the main University Reception for ‘signing in’and directions. If you are intending to visit as a group, then you should book a visit with the HWEHT either by sending an email or leaving a message on 01905 8555184.  Note that car parking is limited, especially during University term-time,  and there may be a modest car parking charge. payable There is no fee for visiting the garden itself, although donations to the Earth Heritage Trust are always appreciated!