The Earth Story

Morning tea

Scotland’s Sauropods

Over 170 million years ago, on what is now the northern Scottish island of Skye, Sauropods, some of the largest land animals on Earth walked through shallow coastal lagoon as indicated by several overprinting footprints. The new discovery makes the island of Skye the largest dinosaur site in Scotland and fills an important evolutionary gap in the history of these long-necked animals, which were some of the biggest of the dinosaurs.

Palaeontologists at the University of Edinburgh first identified the tracks in sedimentary rock, representative of a shallow, salt water lagoon environment. The footprints, some which are 70cm in diameter, form part of a larger trackway and are the first sauropod tracks found in Scotland. Until now, the only sauropod fossil material in Scotland came from a few teeth fragments and bone. The tracks have been discovered in multiple rock layers, middle Jurassic in age, suggesting they were left by many dinosaurs over a period of time.

As with any type of ichnofossil (trace fossil) it’s difficult to work out which species of Sauropod dinosaur was responsible for these tracks without any other fossil material. However, the researchers hypothesize they were produced by the distant relatives of a more well-documented species, Diplodocus. Furthermore, it’s estimated that these Sauropods weighed 10 tonnes and were at least 15 metres long. Tracks of are good indications of behavioural ecology, and in this instance clearly indicate these terrestrial dinosaurs waded into coastal lagoons (as was previously assumed).

AHP

Sources http://bit.ly/1NriZgH http://bit.ly/1TrVeWz http://bit.ly/1TrJtiH http://bbc.in/1Iq7F44

Image http://n.pr/1HEwYiD

The Cuillin Mountains

Myths tell the story of how the Cuillin Mountains on the Island of Skye were formed when the Sun flung its spear into the ground. A huge blister appeared and began to swell where the spear had struck the earth. Eventually the blister burst and discharged glowing molten material forming the Black Cuillin. This glowing molten material is the black and ragged gabbro, the type of igneous rock that composes the steep Black Cuillin. The bursting blister concealed the smoother, much lower-lying, snow-covered Red Cuillin, which consists of much lighter colored granite.

Interestingly, this myth correctly describes how a volcanic dome would burst and spew out hot magma. The Cuillin are indeed the remnants of an ancient volcano, eroded by rain and wind. They formed 50-70 million years ago when the Atlantic Ocean widened and the area experienced extreme volcanic upheaval. In this process a chain of volcanoes formed along the west side of the Scottish Highlands. The lava (basalt) welled up from fissures in the earth’s crust and rapidly cooled. Eventually the basalt was injected with dark gabbro, a type of rock which has larger crystals and cools slower because of the surrounding basalt. This is how the rugged Black Cuillin were formed. The gabbro and molten basalt also came into contact with the lower lying crust. The intense heat caused the lower crust to melt and the lava was injected with red/pinkish granite,creating the Red Cuillin.

Sometimes, geological history and creation myths do not differ that much.

-OW-

Image: Copyright Arpingstone. The main ridge of the Black Guilin.

Further reading: Major, Adrienne. 2004. Geomythology. Encyclopedia of Geology. http://bit.ly/1LHAF5O

The Quiraing The landslide visible in the photo is still gently slipping, and is the largest one in Britain. The road winding through the marvellous glacier sculpted landscape of the Isle of Skye at the bottom of the slip needs consequent repairs every year. Skye is located off the Scottish mainland, and Trotternish Ridge is the source of the slide and hosts a popular walking trail. Other landslips are visible in the background, as the forces of erosion repeatedly peel layers off the cliff (known as an escarpment) that then slump down the slope. The ridge probably represents a weak line in the rocks, since its formation is entirely due to this phenomenon.  Five stages of movement have been traced by geomorphologists (those who study the surface shape of the Earth and how it was formed). The rocks are fossil rich Jurassic marine sediments, composed of clays, shales and sandstones, overlain by tertiary basaltic lava flows some 300 metres thick, whose weight peeled the sediments off the cliff. The name comes from the old Norse for round fold, and reputedly sheep were hidden there from raiding Vikings.  Alot of 'the Isles' (as my favourite historian called them, as he navigated a careful and sensitive route through the maze of identities, past and modern, that are present in Yneis Pryrdein) best geology lies north of the Scottish border, and I'm personally grateful I won't need to bring my passport in order to visit it.  Loz Image credit: Dougie Cunningham http://www.rgs.org/OurWork/Schools/Teaching+resources/Key+Stage+3+resources/Adventure+landscapes/A+walk+around+the+Quiraing.htm http://www.isleofskye.com/skye-guide/top-ten-skye-walks/the-quiraing http://www.theskyeguide.com/walking-mainmenu-32/13-moderate-walks/128-quiraing