| 31. | More recently two locations in mid Wales have been selected to globally define stages of the Silurian period.
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| 32. | The rocks underneath Chisholm are two kinds of volcanic rock that erupted from volcanos in the Silurian period.
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| 33. | Acanthodians are a type of ancient fish dating back the late Silurian period, often being called spiny sharks.
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| 34. | It lived in the Silurian period.
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| 35. | The Devonian Period rocks are more common than Silurian Period rocks, making up two thirds of the county.
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| 36. | Over the porphyroids lie various horizontal beds of slate from the Silurian period that are often clayey-sandy on top.
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| 37. | The earliest previously known fossil records of land-dwelling creatures date from the Silurian period some 50 million years later.
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| 38. | In the 1840s fossils of brachiopods and trilobites from the Silurian period were discovered at Woolshed Creek near Duntroon.
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| 39. | These rock formations mainly consist of shales, sandstones, and conglomeratic sandstones that date to the Ordivician and Silurian periods.
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| 40. | Fossils ascribed to the Lycopodiophyta first appear in the Silurian period, along with a number of other vascular plants.
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