Triassic Sandstone & Mudstone

A general view of Cedar Road Quarry in 1997

The first time that I saw this site, way back in 1997, a very brief survey clearly demonstrated that the extensive and easily accessible rock outcrops makes this an ideal site for educational purposes, at all levels. At the time of my visit, a vehicle and a couple of workmen were being gainfully employed in cutting grass, pruning a variety of shrubs and other invasive vegetation - and taking away the large amount of rubbish that inevitably accumulates in very many forgotten geological sites like this.

Sandstone and Mudstone - 2007

On my next visit, 10 years later, whilst producing the Doncaster Geodiversity Assessment, it seemed obvious to me that this former Adventure Playground was no longer actively managed by the local authority - with beer cans and medical syringes just being a few pieces of social debris that could be found there. 

Apart from a few brambles, which stopped me from getting as close enough to a rock outcrop as I would have liked to have done, my former observations concerning the educational value still held true - as there was plenty of rock to be seen.

At this moment - during winter - I had both the time and the technological benefit of using a Global Positioning Device to pinpoint the various places of geological interest that I had seen before, and could still easily see. I also discovered a few Quaternary rocks that I hadn't noticed before.

Glacial Till and Glaciofluvial Deposits

Although the Sherwood Sandstone Group, of Triassic age, forms the bedrock beneath 70% of the borough of Doncaster and it does form gentle escarpments and other topographical features in places, most of it is buried by unconsolidated Quaternary sediments. In the remote eastern part of the borough, this very friable sandstone has been exploited, along with the overlying sand and gravel, for aggregates and it is well exposed in several active and redundant quarries. However, except where seen in railway cuttings, exposures of rock in the public domain are extremely rare.  

 

A general view of Cedar Road Quarry in 2007

When returning again, this month, with students from XP School, I could hardly believe my eyes. Taking into account a very warm, wet year that has disrupted so many of the annual cycles of plants and birds, amongst other things, I just couldn't see a single place where they could readily undertake any of their allotted tasks - without cutting through the overgrowth.

Conservation Meets Education

An old fashioned measuring tool

Out of the blue, I was recently contacted by XP School in Doncaster, to ask if I would be prepared to act as a “geology expert” and accompany a group of first year students on a field trip to investigate the geology around the Don Gorge.

Martin Said, a teacher at the school, was impressed by the Doncaster Geodiversity Assessment that I co-produced for Doncaster MBC in 2007, whilst working for the British Geological Survey. Having previously undertaken a survey of the 26 geological sites that formed the basis of this report back in 1997, with the South Yorkshire RIGS (Regionally Important Geological Sites) Group, I was considered to be the ideal person to undertake this job.

A 20x magnification hand lens

Although a great effort was made by the South Yorkshire RIGS Group to highlight the very best sites in the county for their educational value, none of the sites identified in South Yorkshire had been used by any school for their field trips - to the best of my knowledge - and so I was very pleased to help.

25 students, split into two groups, were taken to 3 sites that were considered to provide the best introduction to the geology of Doncaster.

With each group travelling in an opposite direction, and meeting up for lunch in the middle, a total of 6 hours was spent out in the field to undertake the following tasks:

1)   Measure and draw the rock outcrop.

2)   Annotate the drawings.

3)  Closely investigate the rock outcrop and analyse the lithologies seen.

Grain Size and Roundness Charts

The Next Step...

An example of stone conservation in Whiston

During my trip to Murcia, I had hoped to visit La Unión, Mazarrón and the various World Heritage Sites, where there is some fine rock art, but time was running against me.

I didn’t think about it at the time of my visit, as I walked up and down a few hills, but subsequent research into the minerals and mines of the region has led me to the Polytechnic of Cartagena.

As in England, the mineral wealth of Spain has been largely worked out and graduates in the various geological, mining and related engineering disciplines - in all of the universities - have to look further afield for work. They will need to learn another language to succeed in the international job market and this language will probably be English.

Geological Maps

My work as a geologist and surveyor has encompassed quarrying, construction, restoration, conservation, archaeology and art; this reflects my passion for stone in its many forms. Along the way, I have talked with engineers, architects, surveyors, town planners, stonemasons and sculptors, among a wide variety of other people who share this passion in common with me.

I know that the ICOG and the IGME want Spanish geologists to improve their English language skills, to give them a better chance to improve their opportunities in the global workplace; however, having visited Italy several times and also being interested in its language and culture, places like Sicily and Sardinia also interest me.

The natural stones of Italy

A Virtual Field Trip

The hills in Cartagena

Looking out from El Teatro Romano, you get such a good impression of Cartagena – and why it was so coveted in the ancient history of the Mediterranean region. However, having spent only 5 hours in the city, much of which time was spent wandering around without any real sense of direction or purpose, I barely scratched the surface of its geological and archaeological history.

The Geology of Cartagena

Apart from the obviously regionally metamorphosed rock that I came across within the Roman theatre, I saw only one other rocky outcrop as I passed La Colina de Despeñaperros - one of the five hills within the Muralla de Carlos III. I just recall a jumble of angular rocks, both natural and those that formed part of its walls, which were weathered and eroding – with muddy colours ranging from red, orange, yellow, green and purple - to pink.

Cartagena is well known for its archaeological remains, as I inadvertently discovered, but I had to wait until I undertook some internet research in England, before I could make sense of its geology. The maps available to me show the city as undifferentiated Quaternary deposits, which is clearly not supported by the field evidence, as seen in the Roman theatre - at least. 

As a student of the Spanish language, I have tried to plough my way through some of the academic publications that describe the general geological history of the region, but I have made much more progress using the resources of Google Map.

Calle Gisbert

Zooming in, each hill shows outcrops of pale coloured rock, remodelled with walls but with similar physical characteristics. Street View shows that the rock faces are just crumbling away. 

Along Calle Gisbert, which bisects La Colina de la Concepción and La Colina de Despeñaperro, the road cutting exposes metamorphic rock similar to that seen in the Roman theatre.

The inherent structural instability of this rock is reflected in the various geotechnical engineering works that have been undertaken here - rock netting, large retaining walls and other measures to keep the street safe from falling rock. Wandering back to the bus station, down Subida San José, I should have noticed similar geology but, in reality, I was more concerned about finding something to eat and drink, after a very long walk.

A View Along Subida San José

After a lot of research, I have a reasonable theoretical understanding of the geology in Cartagena and the metamorphosed Triassic rocks that comprise the mountains which flank its harbour - but the precise geology of the five hills still remains a bit of a mystery...