-
You are here:
- Geo Trail
![Geo trail qr code archway 2](https://royalwilliamyard.imgix.net/geo-trail-qr-code-archway-2.jpeg?auto=compress%2Cformat&crop=focalpoint&fit=crop&fp-x=0.5&fp-y=0.5&h=50&q=80&w=100&s=3a3d599cbec19a54dc957e384c80bf23)
Geo Trail
Known for its grand collection of historic buildings, this is only part of the story of Royal William Yard. To find out more, we need to travel back some 380 million years!
Known for its grand collection of historic buildings, this is only part of the story of Royal William Yard. To find out more, we need to travel back some 380 million years!
This area has an incredible history - and you can see for yourself when you take a walk around. Take a stroll along the Geo Trail to uncover the ancient past and geology of the area.
Take a stroll along the Geo Trail, winding around Royal William Yard and along the South West Coast Path at Devil’s Point to uncover more about the past, and the amazing 380 million years of geological history that can be discovered here!
To get involved, collect one of the Geo Trail leaflets from the visitor office at the entrance to Royal William Yard and scan the QR codes you discover. Alternatively, you can view all of the videos here.
![University of Plymouth image close up corals in Plymouth limestone on the Brewhouse building 2](https://royalwilliamyard.imgix.net/University-of-Plymouth-image_-close-up-corals-in-Plymouth-limestone-on-the-Brewhouse-building-2.jpg?auto=compress%2Cformat&crop=focalpoint&fit=crop&fp-x=0.5&fp-y=0.5&h=1200&q=80&w=1200&s=1ca11ee2074b894375b64af93a356fbd 1200w, https://royalwilliamyard.imgix.net/University-of-Plymouth-image_-close-up-corals-in-Plymouth-limestone-on-the-Brewhouse-building-2.jpg?auto=compress%2Cformat&crop=focalpoint&fit=crop&fp-x=0.5&fp-y=0.5&h=1000&q=80&w=1000&s=e9212192c4a1efee37f6ed3ef84063e6 1000w, https://royalwilliamyard.imgix.net/University-of-Plymouth-image_-close-up-corals-in-Plymouth-limestone-on-the-Brewhouse-building-2.jpg?auto=compress%2Cformat&crop=focalpoint&fit=crop&fp-x=0.5&fp-y=0.5&h=800&q=80&w=800&s=602ecb26db84f85edebdae301da3e0b4 800w, https://royalwilliamyard.imgix.net/University-of-Plymouth-image_-close-up-corals-in-Plymouth-limestone-on-the-Brewhouse-building-2.jpg?auto=compress%2Cformat&crop=focalpoint&fit=crop&fp-x=0.5&fp-y=0.5&h=600&q=80&w=600&s=eb4db325c9a35fdb2e03b238f73f0b8c 600w, https://royalwilliamyard.imgix.net/University-of-Plymouth-image_-close-up-corals-in-Plymouth-limestone-on-the-Brewhouse-building-2.jpg?auto=compress%2Cformat&crop=focalpoint&fit=crop&fp-x=0.5&fp-y=0.5&h=400&q=80&w=400&s=42968c9b8e7b3e64b80acb55c8899718 400w, https://royalwilliamyard.imgix.net/University-of-Plymouth-image_-close-up-corals-in-Plymouth-limestone-on-the-Brewhouse-building-2.jpg?auto=compress%2Cformat&crop=focalpoint&fit=crop&fp-x=0.5&fp-y=0.5&h=200&q=80&w=200&s=85f8ab1dd6b9824b595ad001641f8c8d 200w, https://royalwilliamyard.imgix.net/University-of-Plymouth-image_-close-up-corals-in-Plymouth-limestone-on-the-Brewhouse-building-2.jpg?auto=compress%2Cformat&crop=focalpoint&fit=crop&fp-x=0.5&fp-y=0.5&h=100&q=80&w=100&s=93836dddd07ad2dec2ad4c7583ffb359 100w)
What to look for around Royal William Yard
Our Geo Trail will guide you around some of the fascinating fossils and sensational stone in RoyalWilliam Yard, but there are many more that you can spot for yourself. Keep an eye out for white shapes, blobs and outlines in the stone–once you spot a few and know what to look for, you will notice them all over the Yard!
- The warm shallow seas of the Devonian period left their mark on the local limestone and if you look closely, you can see bivalves (shells with two hinged halves like a cockle), several species of hard coral, ridged shells, and stromatoporoid sponges.
- Tiny microfossils known as conodonts (tooth like elements from a small extinct, but enigmatic, eel like creature) and ostracods (small shelled crustaceans) can determine the age of the limestones. They have been found at Devil’s Point, and they date this limestone to 382 million years old.
- It’s not just microfossils that we can find; the limestone here was once a coral reef bound by corals and stromatoporoids, with crinoids (sea lillies) and brachiopods also living in this environment. The species of coral found here are indicative of a tropical environment, telling us a little about the warm, barmy waters that Plymouth once had, a very different environment to today!
![7 super close up of coral in Plymouth limestone Clarence building](https://royalwilliamyard.imgix.net/7-super-close-up-of-coral-in-Plymouth-limestone-Clarence-building.jpeg?auto=compress%2Cformat&crop=focalpoint&fit=crop&fp-x=0.5&fp-y=0.5&h=900&q=80&w=1200&s=4957a54cf1e17d4528177f3fedb38239 1200w, https://royalwilliamyard.imgix.net/7-super-close-up-of-coral-in-Plymouth-limestone-Clarence-building.jpeg?auto=compress%2Cformat&crop=focalpoint&fit=crop&fp-x=0.5&fp-y=0.5&h=750&q=80&w=1000&s=5a383ea8dd922ec978a15d4743ae0a65 1000w, https://royalwilliamyard.imgix.net/7-super-close-up-of-coral-in-Plymouth-limestone-Clarence-building.jpeg?auto=compress%2Cformat&crop=focalpoint&fit=crop&fp-x=0.5&fp-y=0.5&h=600&q=80&w=800&s=24ac0f9fe022bbcfac0d6e95828c7cee 800w, https://royalwilliamyard.imgix.net/7-super-close-up-of-coral-in-Plymouth-limestone-Clarence-building.jpeg?auto=compress%2Cformat&crop=focalpoint&fit=crop&fp-x=0.5&fp-y=0.5&h=450&q=80&w=600&s=2e70086dcc2afb4ee94a5154a9c40e4b 600w, https://royalwilliamyard.imgix.net/7-super-close-up-of-coral-in-Plymouth-limestone-Clarence-building.jpeg?auto=compress%2Cformat&crop=focalpoint&fit=crop&fp-x=0.5&fp-y=0.5&h=300&q=80&w=400&s=1c0d001da1011e131cdd5e9e5df63994 400w, https://royalwilliamyard.imgix.net/7-super-close-up-of-coral-in-Plymouth-limestone-Clarence-building.jpeg?auto=compress%2Cformat&crop=focalpoint&fit=crop&fp-x=0.5&fp-y=0.5&h=150&q=80&w=200&s=4838dfa7cfe45c17ed2244d5be630075 200w, https://royalwilliamyard.imgix.net/7-super-close-up-of-coral-in-Plymouth-limestone-Clarence-building.jpeg?auto=compress%2Cformat&crop=focalpoint&fit=crop&fp-x=0.5&fp-y=0.5&h=75&q=80&w=100&s=e8cc4cc5b45efb5669ef7f19727ca5ec 100w)
![Geo trail qr code](https://royalwilliamyard.imgix.net/geo-trail-qr-code.jpeg?auto=compress%2Cformat&crop=focalpoint&fit=crop&fp-x=0.2716&fp-y=0.4909&h=900&q=80&w=1200&s=6f786a058d2988d9f34fb9368c5fe215 1200w, https://royalwilliamyard.imgix.net/geo-trail-qr-code.jpeg?auto=compress%2Cformat&crop=focalpoint&fit=crop&fp-x=0.2716&fp-y=0.4909&h=750&q=80&w=1000&s=5f6dec5f5ddf332aad53300589e3273c 1000w, https://royalwilliamyard.imgix.net/geo-trail-qr-code.jpeg?auto=compress%2Cformat&crop=focalpoint&fit=crop&fp-x=0.2716&fp-y=0.4909&h=600&q=80&w=800&s=d0a341752f9c91c788a3ce5eee8c7290 800w, https://royalwilliamyard.imgix.net/geo-trail-qr-code.jpeg?auto=compress%2Cformat&crop=focalpoint&fit=crop&fp-x=0.2716&fp-y=0.4909&h=450&q=80&w=600&s=c3588995667ef9a61c7d01b27078eb04 600w, https://royalwilliamyard.imgix.net/geo-trail-qr-code.jpeg?auto=compress%2Cformat&crop=focalpoint&fit=crop&fp-x=0.2716&fp-y=0.4909&h=300&q=80&w=400&s=d9c8ef86d27d6ee308387c1e46da6403 400w, https://royalwilliamyard.imgix.net/geo-trail-qr-code.jpeg?auto=compress%2Cformat&crop=focalpoint&fit=crop&fp-x=0.2716&fp-y=0.4909&h=150&q=80&w=200&s=f8529b2170a9a09b3a6f2e6cefd3f694 200w, https://royalwilliamyard.imgix.net/geo-trail-qr-code.jpeg?auto=compress%2Cformat&crop=focalpoint&fit=crop&fp-x=0.2716&fp-y=0.4909&h=75&q=80&w=100&s=3abbb84634a5afe37746e07de651e79b 100w)
Digging even deeper
As you look at Royal William Yard from the marina, you see that buildings were made symmetrically either side of the Melville building, framing it as the centrepiece. ‘Smarter’ granite was used at the front, while local limestone was used for the back of the buildings. This made sure it looked especially impressive when the Admiral and high-ranking naval officials looked at it from their base at Mount Wise.
Granite is a fantastic building stone due to its hard wearing properties, and that is all down to its minerals. Predominantly made from quartz (the transparent/grey crystals), feldspar (the white crystals) and mica (the black shiny crystals) this rocks is both strong and attractive. Here in Devon, we have a large source of granite, which can be found on Dartmoor. We can see Dartmoor’s high ground easily from Plymouth, and its great height and expanse is due to this large granite mass.
The granite we see here at the Royal William Yard tells quite a story. It is a fantastic building stone, it created a huge mining industry that continues today, and it makes a unique landscape visited by millions every year. Visiting Dartmoor you will see numerous quarries, from smaller ones like those seen at Burrator, to huge industrial excavations seen at Foggintor, Merrivale and Haytor. The stones quarried from these sites formed Nelsons Column, London Bridge, and the British Museum.
![34 large plagioclase phenocrysts in granite Brewhouse building columns](https://royalwilliamyard.imgix.net/34-large-plagioclase-phenocrysts-in-granite-Brewhouse-building-columns.jpg?auto=compress%2Cformat&crop=focalpoint&fit=crop&fp-x=0.5&fp-y=0.5&h=900&q=80&w=1200&s=7c3a8e85c5e7a23d55b780480da86d32 1200w, https://royalwilliamyard.imgix.net/34-large-plagioclase-phenocrysts-in-granite-Brewhouse-building-columns.jpg?auto=compress%2Cformat&crop=focalpoint&fit=crop&fp-x=0.5&fp-y=0.5&h=750&q=80&w=1000&s=ba33a301f0279b83d11b52ce76b04e63 1000w, https://royalwilliamyard.imgix.net/34-large-plagioclase-phenocrysts-in-granite-Brewhouse-building-columns.jpg?auto=compress%2Cformat&crop=focalpoint&fit=crop&fp-x=0.5&fp-y=0.5&h=600&q=80&w=800&s=a440075b90a6323146d5dcd486b5a4c5 800w, https://royalwilliamyard.imgix.net/34-large-plagioclase-phenocrysts-in-granite-Brewhouse-building-columns.jpg?auto=compress%2Cformat&crop=focalpoint&fit=crop&fp-x=0.5&fp-y=0.5&h=450&q=80&w=600&s=9bf1c35a01d7815f05a3efe0473e1ce7 600w, https://royalwilliamyard.imgix.net/34-large-plagioclase-phenocrysts-in-granite-Brewhouse-building-columns.jpg?auto=compress%2Cformat&crop=focalpoint&fit=crop&fp-x=0.5&fp-y=0.5&h=300&q=80&w=400&s=b4faf96c8307c8f095fea4f1957e4766 400w, https://royalwilliamyard.imgix.net/34-large-plagioclase-phenocrysts-in-granite-Brewhouse-building-columns.jpg?auto=compress%2Cformat&crop=focalpoint&fit=crop&fp-x=0.5&fp-y=0.5&h=150&q=80&w=200&s=659a8e88bd6d554162813ed62242a032 200w, https://royalwilliamyard.imgix.net/34-large-plagioclase-phenocrysts-in-granite-Brewhouse-building-columns.jpg?auto=compress%2Cformat&crop=focalpoint&fit=crop&fp-x=0.5&fp-y=0.5&h=75&q=80&w=100&s=1937607db6182524c434bf4629c7383d 100w)
![Geo trail qr code rocks](https://royalwilliamyard.imgix.net/geo-trail-qr-code-rocks.jpeg?auto=compress%2Cformat&crop=focalpoint&fit=crop&fp-x=0.1973&fp-y=0.6377&h=900&q=80&w=1200&s=2f8a1ef6cb82d3979522a7d87a96da0f 1200w, https://royalwilliamyard.imgix.net/geo-trail-qr-code-rocks.jpeg?auto=compress%2Cformat&crop=focalpoint&fit=crop&fp-x=0.1973&fp-y=0.6377&h=750&q=80&w=1000&s=e0054531b80c821cbb2ce1a8ef018487 1000w, https://royalwilliamyard.imgix.net/geo-trail-qr-code-rocks.jpeg?auto=compress%2Cformat&crop=focalpoint&fit=crop&fp-x=0.1973&fp-y=0.6377&h=600&q=80&w=800&s=bcff77bf1fa5c8f05fbd277e77807c69 800w, https://royalwilliamyard.imgix.net/geo-trail-qr-code-rocks.jpeg?auto=compress%2Cformat&crop=focalpoint&fit=crop&fp-x=0.1973&fp-y=0.6377&h=450&q=80&w=600&s=87caa908a222be9edb5f866a84580bb5 600w, https://royalwilliamyard.imgix.net/geo-trail-qr-code-rocks.jpeg?auto=compress%2Cformat&crop=focalpoint&fit=crop&fp-x=0.1973&fp-y=0.6377&h=300&q=80&w=400&s=fe26463d3214619691a6cb067cedbd76 400w, https://royalwilliamyard.imgix.net/geo-trail-qr-code-rocks.jpeg?auto=compress%2Cformat&crop=focalpoint&fit=crop&fp-x=0.1973&fp-y=0.6377&h=150&q=80&w=200&s=70b45341376ba864a5550d3031839e3b 200w, https://royalwilliamyard.imgix.net/geo-trail-qr-code-rocks.jpeg?auto=compress%2Cformat&crop=focalpoint&fit=crop&fp-x=0.1973&fp-y=0.6377&h=75&q=80&w=100&s=38d9cdc648541183e6746ec5e06f5b63 100w)
Great Granite
As you look at Royal William Yard from the marina, you see that buildings were made symmetrically either side of the Melville building, framing it as the centrepiece. ‘Smarter’ granite was used at the front, while local limestone was used for the back of the buildings. This made sure it looked especially impressive when the Admiral and high-ranking naval officials looked at it from their base at Mount Wise.
Granite is a fantastic building stone due to its hard wearing properties, and that is all down to its minerals. Predominantly made from quartz (the transparent/grey crystals), feldspar (the white crystals) and mica (the black shiny crystals) this rocks is both strong and attractive. Here in Devon, we have a large source of granite, which can be found on Dartmoor. We can see Dartmoor’s high ground easily from Plymouth, and its great height and expanse is due to this large granite mass.
The granite we see here at the Royal William Yard tells quite a story. It is a fantastic building stone, it created a huge mining industry that continues today, and it makes a unique landscape visited by millions every year. Visiting Dartmoor you will see numerous quarries, from smaller ones like those seen at Burrator, to huge industrial excavations seen at Foggintor, Merrivale and Haytor. The stones quarried from these sites formed Nelsons Column, London Bridge, and the British Museum.
![7 super close up of coral in Plymouth limestone Clarence building](https://royalwilliamyard.imgix.net/7-super-close-up-of-coral-in-Plymouth-limestone-Clarence-building.jpeg?auto=compress%2Cformat&crop=focalpoint&fit=crop&fp-x=0.5&fp-y=0.5&h=900&q=80&w=1200&s=4957a54cf1e17d4528177f3fedb38239 1200w, https://royalwilliamyard.imgix.net/7-super-close-up-of-coral-in-Plymouth-limestone-Clarence-building.jpeg?auto=compress%2Cformat&crop=focalpoint&fit=crop&fp-x=0.5&fp-y=0.5&h=750&q=80&w=1000&s=5a383ea8dd922ec978a15d4743ae0a65 1000w, https://royalwilliamyard.imgix.net/7-super-close-up-of-coral-in-Plymouth-limestone-Clarence-building.jpeg?auto=compress%2Cformat&crop=focalpoint&fit=crop&fp-x=0.5&fp-y=0.5&h=600&q=80&w=800&s=24ac0f9fe022bbcfac0d6e95828c7cee 800w, https://royalwilliamyard.imgix.net/7-super-close-up-of-coral-in-Plymouth-limestone-Clarence-building.jpeg?auto=compress%2Cformat&crop=focalpoint&fit=crop&fp-x=0.5&fp-y=0.5&h=450&q=80&w=600&s=2e70086dcc2afb4ee94a5154a9c40e4b 600w, https://royalwilliamyard.imgix.net/7-super-close-up-of-coral-in-Plymouth-limestone-Clarence-building.jpeg?auto=compress%2Cformat&crop=focalpoint&fit=crop&fp-x=0.5&fp-y=0.5&h=300&q=80&w=400&s=1c0d001da1011e131cdd5e9e5df63994 400w, https://royalwilliamyard.imgix.net/7-super-close-up-of-coral-in-Plymouth-limestone-Clarence-building.jpeg?auto=compress%2Cformat&crop=focalpoint&fit=crop&fp-x=0.5&fp-y=0.5&h=150&q=80&w=200&s=4838dfa7cfe45c17ed2244d5be630075 200w, https://royalwilliamyard.imgix.net/7-super-close-up-of-coral-in-Plymouth-limestone-Clarence-building.jpeg?auto=compress%2Cformat&crop=focalpoint&fit=crop&fp-x=0.5&fp-y=0.5&h=75&q=80&w=100&s=e8cc4cc5b45efb5669ef7f19727ca5ec 100w)
![University of Plymouth image abundant corals and stromatoporoids in Plymouth limestone of the Brewhouse building 2](https://royalwilliamyard.imgix.net/University-of-Plymouth-image_-abundant-corals-and-stromatoporoids-in-Plymouth-limestone-of-the-Brewhouse-building-2.jpg?auto=compress%2Cformat&crop=focalpoint&fit=crop&fp-x=0.5&fp-y=0.5&h=900&q=80&w=1200&s=62cbcd0351b43fa04b6d4005f4e2b516 1200w, https://royalwilliamyard.imgix.net/University-of-Plymouth-image_-abundant-corals-and-stromatoporoids-in-Plymouth-limestone-of-the-Brewhouse-building-2.jpg?auto=compress%2Cformat&crop=focalpoint&fit=crop&fp-x=0.5&fp-y=0.5&h=750&q=80&w=1000&s=796004cc6f43144b10213e5b1a8d5527 1000w, https://royalwilliamyard.imgix.net/University-of-Plymouth-image_-abundant-corals-and-stromatoporoids-in-Plymouth-limestone-of-the-Brewhouse-building-2.jpg?auto=compress%2Cformat&crop=focalpoint&fit=crop&fp-x=0.5&fp-y=0.5&h=600&q=80&w=800&s=21a733eb3a247ff12e97867999a2488b 800w, https://royalwilliamyard.imgix.net/University-of-Plymouth-image_-abundant-corals-and-stromatoporoids-in-Plymouth-limestone-of-the-Brewhouse-building-2.jpg?auto=compress%2Cformat&crop=focalpoint&fit=crop&fp-x=0.5&fp-y=0.5&h=450&q=80&w=600&s=1ac68bfa1e1d85853f246a2f81efdd26 600w, https://royalwilliamyard.imgix.net/University-of-Plymouth-image_-abundant-corals-and-stromatoporoids-in-Plymouth-limestone-of-the-Brewhouse-building-2.jpg?auto=compress%2Cformat&crop=focalpoint&fit=crop&fp-x=0.5&fp-y=0.5&h=300&q=80&w=400&s=07e86c471fd62cb4a83dac0d20d4a32e 400w, https://royalwilliamyard.imgix.net/University-of-Plymouth-image_-abundant-corals-and-stromatoporoids-in-Plymouth-limestone-of-the-Brewhouse-building-2.jpg?auto=compress%2Cformat&crop=focalpoint&fit=crop&fp-x=0.5&fp-y=0.5&h=150&q=80&w=200&s=51cd3400341a8ab09b1f3322eb99114e 200w, https://royalwilliamyard.imgix.net/University-of-Plymouth-image_-abundant-corals-and-stromatoporoids-in-Plymouth-limestone-of-the-Brewhouse-building-2.jpg?auto=compress%2Cformat&crop=focalpoint&fit=crop&fp-x=0.5&fp-y=0.5&h=75&q=80&w=100&s=2b3224de18abb3039a2de2ae060d5a30 100w)
Magnificent mountains
300 million years ago, a period of widespread mountain building was taking place across what is now northern Europe. The continents of Laurussia and Gondwana collided to form the supercontinent Pangea, and the shallow sea that our Plymouth limestone was forming in closed. This phase of mountain building was known as the Variscan orogeny, and would have led to a mountain range across Europe with small mountains across Devon and Cornwall.
These impressive mountains have since eroded away, but evidence of them can be seen in the amazing contortions of the rocks (geologists call these folds) that you can observe on the north coast of Devon and Cornwall at Hartland Quay and Millook Haven - and also more locally at Bovisand Bay.
This intense mountain building also led to changes in the Earth’s crust. These changes caused the lower crust to start to melt, and the formation of magma which rose up towards the surface. As it moved upwards into the upper crust it formed widespread sheets, which cooled slowly and the large crystals we see in the granite today began to form. Over time the sediments and rocks above the granite eroded and exposed the granite landscape we see on Dartmoor today. We can find similar granite exposed at Bodmin Moor, St Austell, Carnmenellis and Land’s End, an area overall that is 250km long, 20-40km wide and up to 10km thick!
![Rwy archway tunnel firestone](https://royalwilliamyard.imgix.net/rwy-archway-tunnel-firestone.jpg?auto=compress%2Cformat&crop=focalpoint&fit=crop&fp-x=0.5&fp-y=0.5&h=825&q=80&w=1200&s=94d29fa4f097dc44fcb4928d545c94de 1200w, https://royalwilliamyard.imgix.net/rwy-archway-tunnel-firestone.jpg?auto=compress%2Cformat&crop=focalpoint&fit=crop&fp-x=0.5&fp-y=0.5&h=688&q=80&w=1000&s=82bfc5b127b2c041732576e7d7795053 1000w, https://royalwilliamyard.imgix.net/rwy-archway-tunnel-firestone.jpg?auto=compress%2Cformat&crop=focalpoint&fit=crop&fp-x=0.5&fp-y=0.5&h=550&q=80&w=800&s=0c8bf01f3065922e59a4d61b8882b0e4 800w, https://royalwilliamyard.imgix.net/rwy-archway-tunnel-firestone.jpg?auto=compress%2Cformat&crop=focalpoint&fit=crop&fp-x=0.5&fp-y=0.5&h=413&q=80&w=600&s=e06555c0fa4ce2145a0fee02f946b32e 600w, https://royalwilliamyard.imgix.net/rwy-archway-tunnel-firestone.jpg?auto=compress%2Cformat&crop=focalpoint&fit=crop&fp-x=0.5&fp-y=0.5&h=275&q=80&w=400&s=e18dc1f8643cfd7fba889f6054793566 400w, https://royalwilliamyard.imgix.net/rwy-archway-tunnel-firestone.jpg?auto=compress%2Cformat&crop=focalpoint&fit=crop&fp-x=0.5&fp-y=0.5&h=138&q=80&w=200&s=0dc2ca503eaf1fd6e19403e7f5b44390 200w, https://royalwilliamyard.imgix.net/rwy-archway-tunnel-firestone.jpg?auto=compress%2Cformat&crop=focalpoint&fit=crop&fp-x=0.5&fp-y=0.5&h=69&q=80&w=100&s=3c169e9bbc972ca44e322f95b9814726 100w)
Our very own volcanos
Drake's Island is a Plymouth landmark, but not many people realise it is actually made in part, of Basalt, which is formed from lava! This is an igneous rock, made through lava cooling and solidifying, and its presence indicates that significant volcanic activity was taking place in Plymouth during the Devonian period.
The volcanic rocks we find on Drake’s Island are not just basalt though, they are made up of rocks known as ‘tuff’ which is a volcanic deposit of the ash and tephra that is ejected from a volcano. Containing course and fine grained of pumice and lava with gas bubbles filled with calcite, and pieces of hyaloclastite (fragmented lava containing volcanic glass) we can determine that these volcanoes erupted underwater, and on to our shallow coral reefs.
We can date this volcanic activity as occurring between 390 and 385 million years ago, at the same time as the coral and stromatoporoid reefs were flourishing! In fact it may be due to earlier volcanism over a significant period of time that the Plymouth limestone reefs could form! Scientific studies suggest that the Plymouth limestone lies on volcanic rocks up to 300m thick. The eruption of these extensive lavas formed elevated areas, providing the perfect shallow water environment on which the Plymouth limestone reefs could form.
![7 super close up of coral in Plymouth limestone Clarence building](https://royalwilliamyard.imgix.net/7-super-close-up-of-coral-in-Plymouth-limestone-Clarence-building.jpeg?auto=compress%2Cformat&crop=focalpoint&fit=crop&fp-x=0.5&fp-y=0.5&h=825&q=80&w=1200&s=a15c62770b8025810f5178efdd763deb 1200w, https://royalwilliamyard.imgix.net/7-super-close-up-of-coral-in-Plymouth-limestone-Clarence-building.jpeg?auto=compress%2Cformat&crop=focalpoint&fit=crop&fp-x=0.5&fp-y=0.5&h=688&q=80&w=1000&s=a5fd35ff7abef39a368b726f06cc33e4 1000w, https://royalwilliamyard.imgix.net/7-super-close-up-of-coral-in-Plymouth-limestone-Clarence-building.jpeg?auto=compress%2Cformat&crop=focalpoint&fit=crop&fp-x=0.5&fp-y=0.5&h=550&q=80&w=800&s=6a8231a7e2d0db683ae1414fbcf75674 800w, https://royalwilliamyard.imgix.net/7-super-close-up-of-coral-in-Plymouth-limestone-Clarence-building.jpeg?auto=compress%2Cformat&crop=focalpoint&fit=crop&fp-x=0.5&fp-y=0.5&h=413&q=80&w=600&s=995edf54abd04256ee8176547550432a 600w, https://royalwilliamyard.imgix.net/7-super-close-up-of-coral-in-Plymouth-limestone-Clarence-building.jpeg?auto=compress%2Cformat&crop=focalpoint&fit=crop&fp-x=0.5&fp-y=0.5&h=275&q=80&w=400&s=3210390c8fe63fd6020ce0d84b0efde3 400w, https://royalwilliamyard.imgix.net/7-super-close-up-of-coral-in-Plymouth-limestone-Clarence-building.jpeg?auto=compress%2Cformat&crop=focalpoint&fit=crop&fp-x=0.5&fp-y=0.5&h=138&q=80&w=200&s=a5c28be7365ffcf84bbc877331945e7f 200w, https://royalwilliamyard.imgix.net/7-super-close-up-of-coral-in-Plymouth-limestone-Clarence-building.jpeg?auto=compress%2Cformat&crop=focalpoint&fit=crop&fp-x=0.5&fp-y=0.5&h=69&q=80&w=100&s=6b60aaeafb776eaf545c5bbf9c0aa0e5 100w)
Discovering Devil’s Point
At parts of Devil’s Point, especially as you get closer to the sea, you can spy the dark, jagged natural rock. This is the original bedrock, Plymouth limestone, the same limestone that we can see used in the buildings at Royal William Yard.
The limestone here at Devil’s Point and that you can see outcropping over at Cremyll and all the way along the Hoe and across to Mount Batten has been researched extensively. The plants and flowers also tell us about the geology that lies beneath them. The limestone creates alkali soils perfect conditions for some of the plants we see here – it has more than 80 varieties of wild flowers.
Samphire grows there, although you have to be quick, as the young leaves in early Spring are the edible ones! Another tasty plant is Alexanders, which the Romans used as an alternative to celery. You can also spot Buck’s Horn Plantain, Field Eryngo, Tree Mallow and Rock Spurrey – look for the sign along the South West Coast path with pictures to help you spy them.