Fauna of a Silurian Canyon-fill
17th February 2008

The laminated siltstone fills of Silurian canyon heads in the Leintwardine district (Herefordshire, UK) have been famous since Victorian times for their diverse echinoderm and arthropod faunas.

Here I show some examples of the fauna, together with stratigraphic and palaeogeographic context and 3D model visualizations of the depositional setting (Smith, R.D.A. 2003. Slope-related depositional systems of the Welsh Basin and Welsh Borderland: A field excursion, 30th April to 2nd May 2003. International conference on submarine slopes, Liverpool.)

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Isopach and palaeogeographic map showing Ludlow Series basin and adjacent shelf for the basal Ludfordian Stage, Ludlow Series. Notice the embayment in the Leintwardine to Wigmore area, produced by submarine erosion. Note the steep gradient in isochores across the trace of the Church Stretton Fault.
Isopach and palaeogeographic map showing Ludlow Series basin and adjacent shelf for the basal Ludfordian Stage, Ludlow Series. Notice the embayment in the Leintwardine to Wigmore area, produced by submarine erosion. Note the steep gradient in isochores across the trace of the Church Stretton Fault.
Eastward migration of the shelf-slope break in the Silurian Welsh Basin (Smith 2003).
Eastward migration of the shelf-slope break in the Silurian Welsh Basin (Smith 2003).
 3D computer model of the shelf edge erosion in the Leintwardine to Wigmore area. From Smith (2003).
3D computer model of the shelf edge erosion in the Leintwardine to Wigmore area. From Smith (2003).
 3D view of the composite lower Leintwardine shelf edge erosion surface showing the shelfal stratigraphy preserved beneath. The Wigmore Rolls Formation, in grey, is of Wenlock Series Age. Depth of erosion reaches approximately 250 m. From Smith (2003).
3D view of the composite lower Leintwardine shelf edge erosion surface showing the shelfal stratigraphy preserved beneath. The Wigmore Rolls Formation, in grey, is of Wenlock Series Age. Depth of erosion reaches approximately 250 m. From Smith (2003).
Finely laminated calcareous siltstones with ripple cross-laminated coarse siltstones.
Finely laminated calcareous siltstones with ripple cross-laminated coarse siltstones.
 Current-aligned Saetograptus leintwardinensis graptolites with crinoid arm from the fill of a submarine canyon. Lower Leintwardine Formation. Ludlow Series, Upper Silurian. Leintwardine, Herefordshire, UK.
Current-aligned Saetograptus leintwardinensis graptolites with crinoid arm from the fill of a submarine canyon. Lower Leintwardine Formation. Ludlow Series, Upper Silurian. Leintwardine, Herefordshire, UK.
 Current-aligned Saetograptus leintwardinensis graptolites with brachiopod from the fill of a submarine canyon. Lower Leintwardine Formation. Ludlow Series, Upper Silurian. Leintwardine, Herefordshire, UK.
Current-aligned Saetograptus leintwardinensis graptolites with brachiopod from the fill of a submarine canyon. Lower Leintwardine Formation. Ludlow Series, Upper Silurian. Leintwardine, Herefordshire, UK.
 Paraphragmites ibex, 37 mm cephalopod with complete mouth border.
Paraphragmites ibex, 37 mm cephalopod with complete mouth border.
Bdellacoma vermiformis.
Bdellacoma vermiformis.
 Limuloides limuloides, the prosoma of a primitive horseshoe crab. Church Hill, Leintwardine. Collected April 1983.
Limuloides limuloides, the prosoma of a primitive horseshoe crab. Church Hill, Leintwardine. Collected April 1983.
 Ceratiocaris. Brandon Hill.
Ceratiocaris. Brandon Hill.
 Protoscolex latus Bather 1920, an extremely rare worm, 18 mm long, once thought to be an oligochaete, from the Ludlow Series, Lower Leintwardine Formation, Church Hill, Leintwardine, Herefordshire, UK.
Protoscolex latus Bather 1920, an extremely rare worm, 18 mm long, once thought to be an oligochaete, from the Ludlow Series, Lower Leintwardine Formation, Church Hill, Leintwardine, Herefordshire, UK.
Current aligned ophiuroid and graptolites. Church Hill. Specimen donated to Ludlow Museum.
Current aligned ophiuroid and graptolites. Church Hill. Specimen donated to Ludlow Museum.
 In situ current aligned orthoconic cephalopods with Sphaerirynchia brachiopods and a Ceratiocaris telson. Brandon Hill, near Leintwardine. The tapered ends of the orthocones point up-palaeocurrent towards ENE. The phyllocarid telson has adopted an approximately flow-transverse orientation.
In situ current aligned orthoconic cephalopods with Sphaerirynchia brachiopods and a Ceratiocaris telson. Brandon Hill, near Leintwardine. The tapered ends of the orthocones point up-palaeocurrent towards ENE. The phyllocarid telson has adopted an approximately flow-transverse orientation.
 A series of
A series of "skip marks" interpreted to record the bouncing of a phyllocarid along the sea floor under the influence of a gentle current. Church Hill. Specimen donated to Ludlow Museum.
 Current aligned lingulids and rhynchonellid brachiopods. Church Hill.
Current aligned lingulids and rhynchonellid brachiopods. Church Hill.
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