Overview of environment - a warm climate with low sea levels and a high amount of oxygen in the atmosphere leading to the development of extremely large plants and insects. The earth's climate shifted constantly between glacial and interglacial climates, similar to today.
Significant events - the continents collided to form Pangea, leading to many orogenies (the crust folding to form mountains), at the end of this period the Carboniferous rainforest collapsed due to climate change.
Period 2 Silurian
Silurian Period - 443-416 million years ago
Overview of environment - a warm and stable climate with the optimum amount of oxygen to create ozone and high sea levels, many of the continents were flooded, leading to shallow seas and mound like reefs with a vast expanse of fish.
Significant events - the evolution and diversification of fish (a rapid spread of jawless fish, the first appearance of freshwater fish and fish with jaws)
Period 3 Unconformity
Unconformity - approx. 420-320 million years ago
100 mya gap - here is a gap of 100 mya where we have no geological information, we believe that all of the rocks over this period were deposited and then weathered and eroded away, leaving no record for geologists today. We call this an unconformity.
Strata 10 Silurian Gornal Grit
Silurian Gornal Grit
A type of sandstone laid down in a river delta 420 million years ago, it is one of the hardest and most durable rock types found anywhere in the Black Country. As a result, it was widely employed as a building stone in the local area – and can still be seen in numerous 19th century walls and churches.
The black-and-white photograph shows an oblique view of Ruiton Quarry in Upper Gornal in the summer of 1921, where the Gornal Grit was being worked for building stone. A pile of roughly dressed stone blocks is visible in the lower left.
Strata 11 Silurian mudstone
Silurian mudstone
Calcareous mudstones of the shelf contain a rich fossil fauna that includes bivalves, brachiopods and trilobites. Reefs, built up by corals, crinoids, stromatoporoids and bryozoans.
In this photograph of a small hand specimen of Silurian calcareous mudstone, thin laminations (fine layers) can be seen flaking off the surface, and the ribbed shells of several fossil brachiopods are visible, peeking out of the rock.
Silurian limestones or dolomites (the latter altered from limestone by partial secondary substitution of magnesium for calcium in the calcium carbonate) are widely quarried for crushed rock.
This limestone contains closely spaced nodules in a grey matrix.
Several fossils are visible in the photograph of a small hand specimen of Silurian limestone from Wren's Nest, a locality famous for fossils. You might be able to spot ribbed, curved brachiopod shells, cylindrical crinoid stems, and both 'stick' and 'net' bryozoans.
Calcareous mudstones of the shelf contain a rich fossil fauna that includes bivalves, brachiopods and trilobites. Reefs, built up by corals, crinoids, stromatoporoids and bryozoans.
In this photograph of a small hand specimen of Silurian calcareous mudstone, thin laminations (fine layers) can be seen flaking off the surface, and the ribbed shells of several fossil brachiopods are visible, peeking out of the rock.
Silurian limestones or dolomites (the later altered from limestone by partial secondary substitution of magnesium for calcium) are widely quarried for crushed rock.
The rippled limestone slabs at the top of the grassy slope in this photo represent the top of the Nodule Limestone at Wren's Nest Nature Reserve. The Upper Quarried Limestone used to occupy the trench in the foreground - as the name suggests, it has now been removed by quarrying and the trench partly infilled.
Silurian limestones or dolomites (the latter altered from limestone by partial secondary substitution of magnesium for calcium in the calcium carbonate) are widely quarried for crushed rock.
This limestone contains closely spaced nodules in a grey matrix.
Silurian Nodular limestone forms the top half of the cliff in this photograph taken at Wren's Nest. This exposure shows the typical knobbly texture of this unit. The well-bedded grey strata below are the older Lower Quarried Limestone.
Silurian limestones or dolomites (the latter altered from limestone by partial secondary substitution of magnesium for calcium in the calcium carbonate) are widely quarried for crushed rock.
The well-bedded grey strata forming the lower half of this cliff at Wren's Nest belong to the older Lower Quarried Limestone. The knobbly rock in the upper part of the cliff is the Silurian Nodular limestone.
Strata 17 Silurian Shale
Silurian Shale
Mudstone layers including the Coalbrookdale Formation, which contains numerous fossils beautifully preserved in calcareous nodules contained within a volcanic ash layer.
This oldest unit at Wren's Nest is not well-exposed, as the mudstones are more easily eroded than the limestones. The exposure in the photograph shows typical slabby shales, dipping steeply towards the observer.
Strata 2 Carboniferous mudstone
Carboniferous mudstone
A sedimentary rock made of very small particles of mud and clay – it is “fine-grained” and often called shale.
The image here shows a cliff exposure in a clay pit of dark grey, upper Carboniferous mudstones (shales) interbedded with paler sandstones. The tougher sandstones weather proud as resistant bands between the softer shales, which form gentler, sloping shelves. The cliff is about 25m high overall. Rusty patches at the base of the cliff are seeps of iron-stained groundwater.
Strata 3 Carboniferous coarse sandstone
Carboniferous coarse sandstone
A type of sandstone that is characterised by its pale yellow to pink colour and composed of fine to medium-grained sand.
The creamy-yellow Carboniferous sandstone sample in the image shows a well-sorted texture, with a narrow range of grain sizes. The darker tan line along the top left edge is alteration due to weathering; the irregular top surface is fresh rock. The smooth lower left face has been cut using a diamond-tipped rock saw, to produce a thick slice of rock from which the thin section was created for scanning.
A sedimentary rock made of very small particles of mud and clay – it is “fine-grained” and often called shale.
The image here shows a cliff exposure in a clay pit of dark grey, upper Carboniferous mudstones (shales) interbedded with paler sandstones. The tougher sandstones weather proud as resistant bands between the softer shales, which form gentler, sloping shelves. The cliff is about 25m high overall. Rusty patches at the base of the cliff are seeps of iron-stained groundwater.
Strata 5 Carboniferous river channel sandstone
Carboniferous river channel sandstone
This rock was formed in a massive river delta, like the Amazon or Nile today. This river was busy dumping millions of tons of grit and sand on Yorkshire and the Midlands, which was eventually turned into this rock.
In the field photograph the fresh rock is pale grey, similar to the weathered surfaces on the right of the image, but viewing with a hand lens reveals numerous brightly-coloured sand-grains and granules. The rusty colours on the left of the exposure are due to iron oxides. Just below the centre of the image is a flat, rust-streaked plane inclined towards the observer: this is a small fault plane known as a slickenside - effectively, a fossil earthquake!
A sedimentary rock made of very small particles of mud and clay – it is “fine-grained” and often called shale.
The image here shows a cliff exposure in a clay pit of dark grey, upper Carboniferous mudstones (shales) interbedded with paler sandstones. The tougher sandstones weather proud as resistant bands between the softer shales, which form gentler, sloping shelves. The cliff is about 25m high overall. Rusty patches at the base of the cliff are seeps of iron-stained groundwater.
Strata 7 Carboniferous coal
Carboniferous coal
Formed in dense and swampy forests, which gave rise to large deposits of peat. Over the eons the peat transformed into rich coal stores in Western Europe and North America.
The image shows a scene of underground coal mining in the nineteenth century, at a coal pit owned by the Earl of Dudley. Note the pillar of rock behind the pit pony, part of the 'pillar and stall' system of mining the coal seams. Coal fuelled the industrial revolution in Britain and the Black Country was at the heart of this surge of industry.
Strata 8 Carboniferous conglomerate
Carboniferous conglomerate
A pebbly rock laid down on the eroded surface of Silurian rocks during the Carboniferous. Streaks of coal in this rock layer represent flattened fossil trees buried in the river channel.
In this view of Brewin's Cutting, Carboniferous strata occupy the upper left hand side of the rock face, above the unconformity marked by the oblique, vegetated step running from upper right down to Jonathan Larwood's feet. Below this surface are Silurian strata.
They have a characteristic purplish red-brown colour because of the iron oxide content and are known as the Old Red Sandstone (ORS) facies.
In this view of Brewin's Cutting, the Silurian strata occupy the lower right hand side of the image, beneath the unconformity marked by the oblique, vegetated step running from upper right down to Jonathan Larwood's feet. Above this unconformity surface are Carboniferous strata.
Formed in dense and swampy forests, which gave rise to large deposits of peat. Over the eons the peat transformed into rich coal stores in Western Europe and North America.
The image shows a scene of underground coal mining in the nineteenth century, at a coal pit owned by the Earl of Dudley. Note the pillar of rock behind the pit pony, part of the 'pillar and stall' system of mining the coal seams. Coal fuelled the industrial revolution in Britain and the Black Country was at the heart of this surge of industry.
Following the meteor that blazed a trail across southern England on the evening of Sunday, 28th February, UK researchers have recovered fragments of meteorite from Winchcombe and the surrounding area. Dr Richard Greenwood, a meteorite researcher at the Open University, was first on the scene to verify one piece of the meteorite that smashed into a resident’s driveway.
He was thrilled when he realized that the meteorite is a rare carbonaceous chondrite – in fact, the UK’s first known fall of this type of meteorite. Further fragments have now been found in the area, their rapid recovery ensuring that these exceptional samples have suffered minimal degradation.
The location of the meteorite was pinpointed by specialized cameras and spotters across the country, part of a citizen science network called UKFAll that was set up for exactly this purpose. Data from this network allowed the meteor’s flight path to be recreated, helping scientists not only to predict where it fell, but also to determine its exact point of origin within the asteroid belt.
Carbonaceous chondrites are the most primitive materials in our solar system, representing the stuff that planets are made of: a melange of minerals and organic compounds – including amino acids. Their unique composition potentially carries important information on the earliest origins of water and the basic ingredients for life.
There are three carbonaceous chondrites in the Europlanet Collection of the Virtual Microscope, so you can explore the textures and mineralogy of this rare class of meteorite. One of these meteorites, Allende, has been called ‘the best studied meteorite in history’ and contains microscopic diamonds that pre-date the solar system. The other examples are Dar al Gani 847, found in Libya, and Lancé, which fell in France in 1872. And who knows? Perhaps we will one day be able to view microscopic images of the Winchcombe meteorite on the Virtual Microscope as well.