A small pit was excavated, probably early in the nineteenth century, to extract the hard rock found here for use as roadstone. The eminent  early geologist Sir Roderick Impey Murchison made a referecne to the ‘pit’ in chapter 31 of his work ‘The Silurian System’ published in 1839. Into the twentieth century, the pit was largely infilled and even planted over with Christmas trees in the 1980’s.

Investigations of the Martley Rock site, in the current century, commenced with a first visit by Dr Paul Olver, July 10th 2004, along with three local residents.  On that visit, Malvern Complex rocks were found in the field and a small pit was dug exposing solid Precambrian rock just below the surface. 

Some years later, in February 2010, Paul Olver organised a further visit comprising representatives from the Woolhope Naturalist Field Club (WNFC Geology Section), Herefordshire and Worcestershire Earth Heritage Trust (H&WEHT) along with the landowners, land user and local residents John Nicklin, Dave Cropp & others.  The main trenching was carried out that day under the auspices of the WNFC, with the kind permission of the Taylor family and sponsored by the land-user.  Encouraged by H&WEHT, residents formed a geological society (The Teme Valley Geological Societ) and the society successfully applied for LEADER funding (a European Union initiative designed to support rural development – the name derived from a French acronym) managed by Worcestershire County Council, to document Martley parish geology and to develop the Martley Rock site as a visitor attraction.

In following years further trenches, 12 in total, were dug. These provided points on the map which could be joined to reveal the likely outcrop pattern of the rocks beneath the entire field. Only the two trenches to be dug, 1 and 2 on the map, remain open.

Just over 300 million years ago – around the close of the Carboniferous period – the area was subject to the sustained extreme force of a mountain building period, an orogeny, named in this case the Variscan Orogeny. This was caused by the progressive collison – over millions of years – between the tectonic plates known as Laurasia and Gondwana.

The palaeo map above shows as overlay of the British Isles to indicate their approximate location within the Laurasia plate at the time of the orogeny. Note the close approximity to the Equator c. 300 million years ago.

Gullet Quarry
Malvern Hills

Pembrokeshire

Gower peninsula

Forest of Dean

In the Malverns why do we see east-west folding and thrusting when the Variscan forces were essentially coming from the south?
The folding in SW England, Mendips and S Wales is predominantly east-west aligned. In the Forest of Dean it is both east-west and north-south (dominant, resulting in a synclinal basin structure.

See the video opposite, of a talk by Carl Stevenson to TVGS in 2022, where the influence of the Midlands Micro-Craton is discussed. The relevant discussion begins around 10 minutes into the video.

Movement on the East Malvern Fault – which has a history going way back beyond the Variscan Orogeny – is very significant.

During the orogeny the crust was under compressional forces, resulting in faults having an upward displacement of their hanging wall. They are behaving as reverse faults. In contrast to a normal fault where the rocks of the hanging wall are displaced downward relative to those of the foot wall.

In the case of the East Malvern Fault, this was accompanied by the development of low angle faults – thrust faults – splaying out into the foot wall. These trusts caused rocks from some distance away from one another to moved into juxtaposition.

Following subsequent millions of years of erosion, we find these effects exposed as rocks of widely differing age in close contact, with older rock on top of younger and sequences of rock repeated, as shown in the diagram below, of a cross-section at Martley Rock viewed westward.

The Moor Cliffs Formation (formerly, and still often called, the Raglan Mudstone) is represented at Martley by purplish mudrocks, largely weathered to stiff red clay, with some green and purple mottled clay.

In the eastern side of the trench at C, these mudstones are sandwiched between the East Malvern Fault zone and a faulted junction with the Carboniferous Halesowen Formation.

On the western side of the trench they are overlain unconformably (a time gap) by the Halesowen Formation.

The Moor Cliffs Formation was deposited on extensive flat low lying coastal plains, crossed by slow meandering rivers, with occasional flood events. Location around 25 degrees south of the Equator on the southern edge of the Laurasia continental plate, with hot semi-arid climate. The sediments were carried from erosion of the rising Caledonian Mountains to the north. These great mountains were the product of the still on-going Caledonian Orogeny associated with the closure of the Iapetus Ocean and the coming together of Laurentia, Avalonia (which included southern Britain) and Baltica.

During the approximately 100 millin years, between the deposition of the Malvern Quartzite and the Moor Cliffs Formation, Avalonia split off from Gondwana and moved northward on the southern edge of the Iapetus Oceanic plate. With the eventual subduction of the Iapetus Ocean plate, Avalonia collided first with Baltica, then Laurentia, producing the Caledonian Orogeny and forming what is often called the Old Red Sandstone Continent.

Photographs of the western end of the trench  (J on the map), taken not long after the trench had been freshly exacvated. Sadly, if you visit the site now you will probably have to be content with the quality of exposure shown in the video. Even so the remarkable colours of the clays of the Halesowen Formation overlying the reds of the Moor Cliffs Formation is still striking.

The grey, yellow and pale green clays of the Halesowen Formation, the different colours represent different states of iron oxidation. One colour absent is red, as these sediments were laid down under water, where there would be less oxygen to form red iron oxides. Streaks of black relate to the presence of a poor quality coal. Indeed the local name for these rocks was the Martley Measures, and there is evidence for shallow coal pits on Berrow Hill and numerous bell pits and shafts a few miles north of Martley,

In the eastern side of the trench at E, the contact between the Halesowen Formation and the Malverns Complex is one of another thrust fault. The Halesowen Formation being thrust over the Malverns complex in a westward direction.

The soft red sandstone of the Helsby Sandstone Formation occupies the opening section of the trench up to the fault zone. To better examine the characteristics of this sandstone it is better to view one of the exposures around the village, for example, The Nubbins as shown here.  Viewed through a hand lens, the sandstone can be seen  to be typically formed of rounded grains of quartz, weakly comented by the iron oxide, which gives the rock its distictive red colour – indicative of a rock laid down on land where it was exposed to the oxygen of the atmosphere.

The Helsby Sandstone was formerly known as the Bromsgrove Sandstone. It is now named after its type location near the village of Helsby in Cheshire.

Post Variscan Orogeny

It is important to remember, the Triassic Helsby Sandstone was deposited after the Variscan Orogeny. The orogeny peaked at the end of the Carboniferous. The following Permian period would have seen massive erosion of the uplifted rocks. What we see today, is effectively the deep roots of the uplift. As the orogeny subsided the crust ‘relaxed’ switching from a compressive to an extensional regime. Faults like the East Malvern Fault, changed their movement direction from reverse to normal and many large basins – rifts – began to open. These basins provided places where sediments accumulated, often to great depth. One susch rift lay to the east of the East Malvern Fault, a structure known as the Worcester Graben (name for a fault bounded rift) which filled wih up to 3km depth of Permian and Triassic sediments. That is what now underlies the wide low lying Severn/Worcester Plain to the east of the Malvern Hills.

Click diagrams to enlarge

The above images and interactive map of Martley Rock can be found in the MartleyRocks app, available on the App Store for iPhones and iPads and on Google Play for Android phones and tablets.

This is in addition to the GeoparkWay app which also includes information on Martley Rock and adjacent areas in the Abberley to Martley walk that can be downloaded into the app.