Ripples Through Time by Andy Harrison

Continue your own story from the celebrated opening:

‘Time is not a line but a dimension like the dimensions of space…’

Time is not a line but a dimension like the dimensions of space.  The three vectors of space showing changes in terms of distance and height.  Time records changes through history and hints at what may lay ahead in the future.

We stopped at a viewpoint next to an interpretation board headed ‘Ripples Through Time’.  Before us, the ground dropped sharply, 20m to 30m, into an old quarry.  It’s bottom covered with greenery and grasses, shrubs and skeletal trees.  In spring and summer months alkaline loving wildflowers such as Scabious and Bee Orchids would add colourful splashes along with Common Daisies, Birdsfoot Trefoil and Meadow Buttercups.

Dominating the quarry floor was a rounded grey rocky mass.  Off to the left a former quarry wall exhibited thin interbedded limestone and mudstone layers dipping off to the west.

Delineating the quarries far edge were thorny bushes, trees, and green painted palisade fencing.  Beyond a low-lying housing estate stretched away like a sea of brown and grey covering the local landscape.  On the far western horizon the land rose once again to another wooded hill.

‘Let us look at our journey so far’, our guide announced.

‘We started our journey from the Wardens Base at Mons Hill Campus, walked to Locality 1 and there saw similar beds to these, but dipping towards the east’. ‘Those beds contained thick limestone strata – The Upper Quarried Limestone and clayey bentonite bands, which we said resulted from volcanic eruptions’.  ‘Continuing to Locality 2, we walked up through time through those thinly layered limestones and mudstones to the Lower Quarried Limestone’. ‘and there we saw more ash layers and large limestone domes, like the one we see before us’.

‘From Locality 2’, he continued ‘we walked west over the flat top of the hill to this location, Locality 10 – called the Ripples Through Time’.

‘So, what do we see here?’

‘Once again, the same thinly bedded mudstone and limestone layers, but now dipping towards the west’.  ‘Also, that large limestone mound in the quarry bottom in another example of the patch reef we saw at Locality 2’.

‘So, what’s going on?’

The rocks before us and what we had seen before had been deposited in a shallow tropical lagoon during the Silurian Period, around 420 million years ago. The Silurian period itself would not be established until 1839 when an eminent geologist, the ‘David Attenborough’ of his day, Sir Roderick Impey Murchison visited this part of the West Midlands. In monetary deals with local miners he obtained rock and fossil specimens that he used to develop his ‘Silurian System’.  This was published in 1839 and launched from Dark Cavern located on Castle Hill.

In 2011, mineralogical radiometric dating was undertaken on samples taken from the volcanic ash layers seen at Localities 1 and 2.  The ash layers at Locality 1 were the oldest and dated at around 428 million years. Walking up through the 32m long cutting at Locality 2 we had traversed through 1 million years of geological time. The youngest ash layers at the top of the cutting giving a date of around 427 million years.

The hill we on was Wren’s Nest Hill at the heart of Dudley.  A natural history, geological and industrial heritage gem.  Very important and very overlooked.

During the Silurian Period, Dudley had sat at around 20° north of the equator. Our guide explained that ‘Where we are, would have been like Australia’s great Barrier Reef today’. ‘Birmingham’, to the east ‘Would have sat on dry land’. ‘Dudley would have sat on the landward side of a tropical lagoon that stretched westwards to the continental shelf’. ‘The edge of that shelf would have been marked by a barrier reef, which we see today as the ridge forming Wenlock Edge in Shropshire’.

The floor of the lagoon would have been home to coral reef mounds between which lay a sandy sea floor littered with shell and skeletal debris.  A myriad of molluscs, arthropods, worms, crinoids and early squid like creatures would have lived amongst the corals.  Their skeletal remains forming the limestone layers we see today.

Ripples within the sandy deposits hint at prehistoric wave activity. Water depths not being more than a few meters for the coral to be able to grow.

The interpretation board before us depicted what the area would have looked like during the Silurian Period. It included a sequence of illustrated panels showed images of the area up through geological time – low lying flood plains and forested swamps, deserts and finally tundra with glaciers in the background.

‘At the end of the Silurian’, our guide continued ‘the landmass that Dudley sat on the northern shore of, collided with another’.  ‘The landmasses known as Avalonia and Baltica and the closing ocean between was the Iapetus’.  ‘The result was a mountain building episode, or orogeny, called the Caledonian’.

For the next 100 million years, Dudley and the Black Country’s geological history would be linked to the tectonic uplift and erosion of a Devonian landmass called the Old Red Sandstone Continent.  The compressional forces of the Caledonian Orogeny contorted the earlier limestone and mudstone layers into a series of single folds, or periclines.  Today these folds form Castle Hill, Wren’s Nest Hill and Hurst’s Hill.

Between the hills lies are low-lying areas represented by Coal Measures strata that were deposited in coastal swamps during the mid to late Carboniferous Period around 330 million years ago.  Around 300 million years ago, Dudley sat on the northern edge of another landmass, which itself was about to be involved in another collision between Laurentia, to the north, and Gondwana, to the south.  As depicted on the interpretation panels, tropical lagoons gave way to forested swamps and low-lying river floodplains.

‘Another mountain building episode, the Variscan orogeny,’ continued our guide ‘ saw the Midlands become part of a supercontinent called Pangaea’.  ‘Then around 200 million years ago this continent began to break up as the North Atlantic opened, resulting in numerous rifted basins forming across England’.

Through the Late Triassic, Jurassic and into the Cretaceous the Midlands sat below sea-level with tropical shallow seas surrounding small islands.  A scene not too dissimilar to what we see around the Florida Keys and the Grand Banks today.  Buried beneath sediment, the Black Country was lifted up one last time during the mid-Tertiary, around 55 to 60 million years ago.  The last panel on the interpretation board depicted the Ice Ages between approximately 2 million and 10,000 years ago.  The warming and cooling, back and forth cycles of glacial ice and water eroding the landscape and shaping it into what we see today.

‘Glacial ice took the top of Wren’s Nest Hill’, said our guide ‘like removing the top off a boiled egg’.

With that we walked down some steps into the quarry bottom.  Knowing better how this landscape had changed through the dimension of time.