= Location of England and Wales The rocks underyling the hills and vales of the immediate landscape formed during a geological period of time called the Silurian (416-444 A globe showing the layout of continents and oceans Artist’s impression of a Silurian sea. Image created by John Watson 430 million years ago. Image copyright to Ron Blakey, million years ago). Back then, the layout of the oceans and continents Colorado Plateau Geosystems, Inc across the Earth looked very different - Britain as we know it today did not By the Silurian a great number of sea creatures had evolved hard external skeletons - trilobites, exist. The land which would eventually form this part of Britain was corals, crinoids, brachiopods, molluscs, and more, but there were no fish or land animals. At times located in the southern tropics on a continental shelf, blanketed in a Deep sea Shallow sea the floor of the tropical sea was, in areas, a waving meadow of generation upon generation of warm, shallow, tropical sea. To the east lay a continent, the Midland A crinoids. Their broken up skeletons alone can produce beds of limestone several metres thick. Snowdon Platform; to the west was a deep ocean, the Welsh Basin. The rock face behind you is composed of a crinoid rich limestone, belonging to the Much Wenlock Irish Sea Limestone Formation. Platform Welshpool Fluctuations in sea level and Arms (food Near complete crinoid fossil in Wenlock Wenlock Edge Midland material input from the land Date Period Epoch Rock Unit gathering) Welsh Platform Limestone. Source - Worcester City Art Crinoids are most commonly known as 'sea-lilies' Basin influenced the types of sediment Pridoli Raglan Mudstone Formation Gallery and Museum geology display Malvern Downton Castle Sandstone Formation collection Llandovery or 'feather-stars'. They are marine animals which B that accumulated on the sea floor. Upper Ludlow Shales Group Ludlow Aymestry Limestone Formation belong to the spiny-skinned group of animals Sediments are usually deposited in Lower Ludlow Shales Group 0mm 20mm 0mm 40mm known as echinoderms. Crinoids, like their series of layers or beds, which may Much Wenlock Limestone Formation relatives the sea urchins, sea cucumbers, brittle Wenlock A sketch map to show the palaeogeography of the wider vary in thickness and character and Coalbrookdale Formation stars and starfish, have a special kind of symmetry Calyx (animal area (above). A cross-section to show the sediments contain features diagnostic of their deposited in the Silurian seas (below) Woolhope Limestone Formation based on five or multiples of five radials, so clearly lives in here) environments. Over time these are Wyche Formation Silurian exhibited by the latter. Stem (each part A B buried and harden into rock, a Llandovery is called an Group Group Trilobite, Calymene (left) and a colonial coral, May Hill Hill May Cowleigh Park process known as diagenesis. Sandstone Formation Favosites (right) in Wenlock Limestone. Source - ossicle; Shallow sea Worcester City Art gallery and Museum geology Crinoids have lived in the world's oceans for at normally the limestones display collection stem is the only Iapetus Ocean Deep sea shales Fownhope Formation least 490 million years. Although they still exist sediments and turbidites 444 part of the A sequence of beds that forms a mappable unit of rock is today, they were much more abundant and creature to be fossilised) known as a 'Formation' and is given a name, for diverse in the past. Complete crinoid fossils are example the Much Wenlock Limestone Formation. A Root sequence of successive Formations that show broadly rare but individual 'polo mint' ossicles which similar characteristic are known collectively as a Epoch, make up the stem are frequently found. Crinoid morphology for example the Wenlock Epoch.

A geological timescale for the Silurian, age given in 0mm 20mm millions of years. Rock units that make up the Crinoidal Wenlock Limestone from Lower Farm Quarry Carbonate productivity was extremely high in the warm Silurian sea, resulting in immediate landscape are written in blue

sequences of limestones and small patch reefs (bioherms). Periodically, the Key tropical sea received influxes of sediments from the adjacent landmass of WoH Triassic sandstones and the Midland Platform, forming thin layers of siltstone and shale between mudstones the layers of limestone. Pulverised shell debris and crinoid fragments Permian breccia WaH within the limestone layers suggest the Wenlock shoreline was prone to 1 Some 140 million years after the Silurian rocks formed they were caught Raglan Mudstone Formation occasional heavy storms and vigorous wave action. up in a period of mountain building, known as the Variscan Orogeny, Deep Upper Ludlow Shales marine 2 5 whose earth movements had a profound effect upon the structural and The continental shelf is made up of many niche environments which Aymestry Limestone 4 influence the resultant rock types that form there. There are a variety of 3 topographical characteristics of the Martley area. The once horizontal Formation different limestones within the Much Wenlock Limestone Formation, layers of limestone and shale that formed in the Silurian sea were Lower Ludlow Shales Continental shelf compressed and folded. Since then they have been ravaged by erosion. each rock type reflecting the particular environment under which it Continental slope Much Wenlock formed. The harder limestones now stand proud as the ridgelines of the Limestone Formation A diagram highlighting the depositional environments on the Abberley Hills, seen here as Rodge Hill to the west and Penny Hill to the RH Coalbrookdale Formation continental shelf. 1) Tidal shelf 2) Storm shelf 3) Carbonate shelf Periodically during the Silurian, the local sea deepened and carbonate north; the softer shales have worn away to form sculpted vales. Geological Fault formation was succeeded by the deposition of large quantities of shales 4) Barrier island 5) Lagoon You are here and mudstones. Such conditions are represented locally in the WaH Walsgrove Hill Coalbrookdale Formation, Lower Ludlow and Upper Ludlow Shales. A B A PeH RH Rodge Hill B PuH Pudford Hill PuH WoH Woodbury Hill

Sketch cross-section along line A-B on map (right). Modified from Groom 1900 PeH Penny Hill Interpretation by Herefordshire and Worcestershire Earth Heritage Trust 500m www.EarthHeritageTrust.org.uk 01905 855184 / [email protected] Sketch geology map of Woodbury, Walsgrove, Penny and Rodge Hills. Registered Charity No 1144354 Modified from Groom 1900