tvrigs.org.uk » Cenozoic

September – Whinstone

admin — Thu, 10 Sep 2009 17:53:12 +0000

Whinstone is a quarryman’s term for a variety of hard, dark-coloured, rocks including basalt and chert. Here, in the Tees Valley and Cleveland, the name refers to a hard rock that is very different from the soft sedimentary strata which make up the majority of the area’s underlying geology.

Around 58 million years ago, as the Atlantic oceanic basin formed, adjacent areas of crust became stretched and weaknesses could be exploited by molten material (magma) being forced into the crust by pressure from below. This magma cooled very quickly surrounded by local rocks and became the Cleveland Dyke.

Stretching for c.350 miles between Mull in Western Scotland and the Tees Valley and North Yorkshire the hot magma cooled to form a dark blue-grey, finely crystalline rock referred to by geologists, more correctly, as dolerite. Dolerite is chemically similar to basalt, the major difference being that basalt is erupted at the Earth’s surface, whereas dolerite solidifies within the Earth’s crust.

Following removal of the overlying strata by erosion, primarily through glaciation, the dyke was exposed at the Earth’s surface. In the west of our region it can be traced crossing the river at Preston-on-Tees, but perhaps its most notable feature occurs near Great Ayton where the more durable rock making up the dyke, and softer Jurassic strata into which it is intruded, exhibit a phenomenon known as differential erosion. The softer sedimentary rock is preferentially removed by erosion leaving the harder whinstone to form a bold ridge called Langbaurgh Ridge.

The geater hardness of whinstone relative to sedimentary rock makes it ideal for use road-stone and cobbles, and it was for this purpose that Leeds City Council leased land around Great Ayton, where the ridge is best developed, in 1869. Large quantities of the rock were quarried at Cliff Rigg, as well as elsewhere along the length of the dyke, for example at Preston-on-Tees, Ingleby Barwick, and at a variety of locations on the North York Moors. The now-abandoned workings today form an unmistakeable scar on the landscape, though the former quarry’s remains allow geologists to study the effects of metamorphism, i.e. the baking of the surrounding sedimentary rock when the hot magma was injected.

February – Woolly Mammoth Tooth.

admin — Tue, 03 Feb 2009 11:38:07 +0000

Mammoth lived on most of the continents in the Northern Hemisphere during the last big ice age 70-10,000 years ago. Woolly Mammoths were about the same size as Indian elephants are today and covered in a layer of coarse hair. They are a good indicator of a cold climate and tundra or Steppe conditions. They are well known about and understood as whole frozen carcasses have been found in several places in Siberia. Mammoths are the symbols of the last ice age and many stories have evolved about them. The Siberian tribes believed that they lived in the centre of the earth and died when they came into contact with air. This explained to them why they never found one alive before the theory of extinction had been developed. Mammoths became extinct due to rapid climate change and large-scale human predation.

Mammoths have six sets of teeth throughout their lifetime. (Much like modern day elephants). They moved forward from the back of the jaw and replaced older worn out teeth as they fell out. This means that there are lots of teeth that can be preserved. Thin enamel plates cemented together. This makes a tall strong, wear resistant tooth.

They are often dredged up from the North Sea. Here they are from a land bridge between England and the Netherlands, which was cut off as sea levels rose 6 – 8,000 years ago. The teeth have then been reworked by the sea bringing them to the surface to be collected by trawlers.

The remains of a species of Dwarf Woolly Mammoths have been found on an island between Russia and North America. These have been dated back to 7,000 – 3,500 at the same time that the pyramids and Stonehenge were being built.

Freebrough Hill

cliff.rigg — Wed, 25 Jun 2003 16:09:20 +0000

Contents

Site Description
Site Map
Site Assessment
Surveyors

Grid Reference NZ 690 127
BGS Sheet 34
OS Sheet 94
Forwarded as RIGS 30/09/2003

View of Freebrough Hill from the lay-by on the A171.

Site Description

Site Status

Description of Geodiversity: An outlier of nearby Moorsholm Rigg to the south with its summit reaching to 250m above sea level and 50m above the surrounding moorland. Freebrough Hill is a natural landform sculpted by glacial ice between c.120,000 and 20,000 years ago during the last (Devensian) glaciation. The outlier comprises Middle Jurassic (Bathonian) Scalby Formation deltaic deposits at its base, around c. 5m of the (Callovian) Cornbrash intervenes, and is succeeded by up to 7m of Osgodby Formation sandstones which cap the hill. The country rock is obscured by glacial deposits in the form of both till (boulder clay) and sand. The locality also has a wealth of well-marked glacial meltwater chanels running W-E across and around Moorsholm Rigg which together constitute evidence of glacial retreat at a point close to Devensian ice’s maximum extent.

PLEASE NOTE: There is NO access to this site without landowner permission.

This said, the hill can be viewed from several points in the locality including the lay-by at NZ 68355 13182 (see image above). The moorland around Moorsholm Rigg south of the hill is open access and good views can be had from here.

Literature References

Wishart, D. Date Unknown; An Interpretation of the Geomorphology of Freebrough Hill. University of Durham.

Barrow, G. 1888; The Geology of North Cleveland: Memoirs of the Geological Survey. HMSO, London. 101p

Ord, J.W. 1846; The History & Antiquities of Cleveland: Comprising The Wapentake Of East And West Langbargh, North Riding, County York. Publisher Unknown.

Smith Fletcher, J. 1901; Picturesque history of Yorkshire: Being an account of the history, topography, antiquities, industries, and modern life of the cities, towns, and villages of the county of York, founded on personal observations made during many journeys through the three ridings, Volume 3. Caxton.

Murray, J. 1882; Handbook for travellers in Yorkshire. J. Murray.

Atkinson, Rev. J.C. Date Unknown; The Last of the Giant Killers: Or, the Exploits of Sir Jack of Danby Dale. Publisher Unknown.

Knox, R. 2009; Descriptions, geological, topographical, and antiquarian in Eastern Yorkshire, Between the Rivers Humber and Tees. Publisher Unknown.

Site Map

Site Assessment

Access and Safety	Comments	Rating
Safety of access	Park in lay-by at NZ 68355 13182	8
Safety of exposure	N/A	-
Restricting conditions	Private Land.	-
Multiple exposure	None.	-
Note	It is strongly suggested that on-site safety be the responsibility of the party leader(s), as the safety information above is given only as a guide.	-

Education and Science	Comments	Rating
Surface processes	Solifluction terraces on slopes.	10
Geomorphology	Glacially derived outlier accompanied by well-marked glacial meltwater channelling nearby.	10
Sedimentary rock	Bathonian Scalby sandstone (deltaic), succeeded by Callovian Cornbrash shale (marine) and Osgodby sandstone (marine).	7
Igneous rock	None.	-
Metamorphic rock	None.	-
Fossils	Excellent examples of shell impressions in Osgodby Formation.	8
Minerals	None specific.	2
Structural features	Small fault of unknown throw cuts the SW flank though this is obscured by glacial till.	-
Stratigraphy	None evident due to glacial till covering.	-

Geodiversity Value	Comments	Rating
Education	Glacial landforms and processes.	5
Scientific	Study by Earth scientists.	8
Historical	The hill is named after the Norse Godess Freya, the Godess of love, beauty, fertility, gold, witchcraft, war and death. It is recorded as being a meeting place for the people of the district, possibly stretching back to Viking days (Barrow, 1888). Archaeological investigations took place in the nineteenth century concluding that the hill is a natural landform. A small quarry has been worked for Osgodby sandstone high on the eastern flank, known to have been abandoned by 1888. Perhaps as an echo of the fact that Freya was the Godess of war, or perhaps accidentally, the hill was used for tank maneouvers during WWII.	5
Aesthetic	A well-known and enigmaitic local landform.	10

Surveyors

2003: Andrew Carter, John Waring, Andy Cooper.

2010: Andy Cooper, Alan Simkins, Beth Andrews.

Dalton Piercey

admin — Tue, 06 May 2003 14:08:11 +0000

Contents

Site Description
Site Map
Site Assessment
Surveyors

Grid Reference NZ 469 307
BGS Sheet 27
OS Sheet 93
Forwarded as RIGS 30/09/2003

Site Description

Site Status SNCI
Description of Geodiversity Natural river-cliff exposure of fluvio-glacial deposits. The cliff reveals an exposure of middle sand, gravels and clays.
Literature References The Geology of the Country Between Durham and West Hartlepool – Dennis Smith 1967

Site Map

Site Assessment

Access and Safety	Comments	Rating
Safety of access	Along footpath to exposure	10
Safety of exposure	Level viewing platform on river bank	10
Restricting conditions	Possible high flow episodes	9
Multiple exposure	Other smaller cliffs downstream	8
Note	It is strongly suggested that on-site safety be the responsibility of the party leader(s), as the safety information above is given only as a guide.

Education and Science	Comments	Rating
Surface processes	Various fluvial and glacial processes	10
Geomorphology	River cliff feature	8
Sedimentary rock	Examples in outwash stratigraphy	2
Igneous rock	Examples in outwash stratigraphy	2
Metamorphic rock	Examples in outwash stratigraphy	2
Fossils	None
Minerals	None specific	2
Structural features	None specific	2
Stratigraphy	Excellent stratigraphical examples	10

Geodiversity Value	Comments	Rating
Education	Fluvial processes and glacial deposit example	10
Scientific	Glacial deposit for Earth scientists	10
Historical	No historical value
Aesthetic	River corridor environment	10

Surveyors

Andrew Carter, John Waring

Stainsby Beck Dyke

admin — Thu, 10 Apr 2003 15:35:29 +0000

Contents

Site Description
Site Map
Site Assessment
Surveyors

Grid Reference NZ 465 146
BGS Sheet 33
OS Sheet 93
Forwarded as RIGS 30/09/2003

Site Description

Site Status SNCI
Description of Geodiversity Stream bed exposure of the Cleveland Dyke
Literature References

Site Map

Site Assessment

Access and Safety	Comments	Rating
Safety of access	On footpath from industrial estate	10
Safety of exposure	On opposite riverbank footpath	10
Restricting conditions	High flow episodes obscure exposure	6
Multiple exposure	Mercia mudstone exposure downstream	7
Note	It is strongly suggested that on-site safety be the responsibility of the party leader(s), as the safety information above is given only as a guide.

Education and Science	Comments	Rating
Surface processes	Various fluvial processes	10
Geomorphology	Various fluvial features	10
Sedimentary rock	None
Igneous rock	Dyke intrusion	10
Metamorphic rock	None apparent
Fossils	None
Minerals	None specific
Structural features	Apparent dip of 2° & NNW orientation	7
Stratigraphy	Tertiary igneous intrusion	5

Geodiversity Value	Comments	Rating
Education	Various fluvial processes	10
Scientific	Small Cleveland Dyke exposure	5
Historical	None
Aesthetic	River corridor environment	10

Surveyors

Andrew Carter, John Waring