Jurassic Coast

Jurassic Coast:

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The Jurassic Yorkshire Coast, also known as the 'Dinosaur Coast', the 'Fossil Coast' or the 'Jurassic Coast', is a stretch of coastline around 35 miles long, starting from Staithes in the north, to Flamborough in East Yorkshire. There is a one kilometre section from the old fishing village of Staithes to the small headland of Old Nab that exposes the Cleveland Ironstone of the Lower Jurassic 'Middle Lias'; the fossiliferous strata there holds a Lower Jurassic marine succession. The Cleveland Ironstone Formation of the Middle Liassic age is also very well exposed and consists of shales with prominant ironstone beds; Siderite nodules can be found in abundace within the shales; beds of Sandstone are present at the village of Staithes, in particularly on the east side at Cowbar Nab; the shales and the Cleveland Ironstone Formation is well exposed in the intertidal ledges and in the vertical cliff, which are easily seen when the tide is out. Fossils: The trace fossils at Old Nab are quite remarkable due their excellent preservation and many excellent trace fossils can also be found on the rock platforms at the foot of an unstable upper cliff of the Whitby Mudstone Formation, shales, at Old Nab; the fossils are found within the debris that has already fallen; some of the fossils that are found there are 120 million years old. What is a fossil? In its simplest form, something dies, or gets trapped, in water or mud, over time, lots of time, the body slowly gets covered with sand, mud or silt; the soft parts decompose and leave a cavity and over millions of years the cavity becomes filled with mineral substances which form a cast of the original creature or plant; unfortunately, due to the great pressure of the overlying covering, the cast can often become deformed. There are a great number of variations to this theme, the creature or plant may die on land and be covered by sand from a high tide, it may be washed into a river, trapped in a mud pit, or it may be covered over by volcanic dust; in some cases the whole thing will not decompose and the fossil will still contain some of the original item, for example as with shells, resins, oils and carbonised remains. The Jurassic Yorkshire Coast Fossils:
Ammonites are the most popular type of fossil found there and resemble coiled snakes; they are also known as 'snakestones'; they can be found along the whole length of coast from Staithes to Scarborough; when alive an ammonite resembled the modern day pearly nautilus, rather like a squid in a shell; the creature only lived in approximately a third of the outer portion of the shell, the rest of the shell being made up of gas filled chambers that acted as bouyancy aids to enable the ammonite to swim without sinking. In the Whitby area ammonites are generally preserved in three ways, they will either be found squashed very flat on the surface of shale, preserved more or less intact inside an ironstone nodule, or preserved in mudstone, usually with the outer whorl intact but the centre squashed; local legend says that the ammonites were formed when the Abbess of Whitby, later St. Hilda, drove a plague of snakes over the cliff at Whitby; the species of ammonite pictured was named Hildoceras in honour of this mythical feat.
Belemnites, also known as 'Devils Thunderbolts' look a bit like bullets; the nearest modern equivalent for the part most commonly found is a cuttlefish bone, often found in Budgie's cages; as with ammonites, the belemnite was a squid like creature but instead of having the ammonite's external shell the hard structure of a belemnite was on the inside; this internal shell is known as the guard. They vary in size and shape, from long thin ones 'Cuspiteuthis tubularis', which can be found on the surface of the shale near to Black Nab in Saltwick Bay, to 'Phragmocones'; the extension to the guard in a belemnite is known as the phragmocone; and because the phragmocone was more delicate than the guard they are more difficult to find, as they are unlikely to have been preserved intact; occasionally though they will be preserved inside an ironstone nodule and more rarely in shale.
Dinosaur Footprints: Footprints are known as 'trace fossils' and are good evidence that dinosaurs once roamed this area at around 160 million years ago, when the area around Whitby was a huge river delta; there were large mudflats there, which dinosaurs walked through leaving footprints; some of this mud dried quickly in the tropical heat capturing the footprints; over time these would have become covered with something like sand; the sand and mud layer then became further buried by even more layers of sand, silt and mud and over time they changed into sandstone and mudstone. The footprints we find nowadays are actually 3D sandstone casts of the original footprints; the best place to look for dinosaur footprints is Burniston Bay near Scarborough; follow the steps down to the beach and then turn left, the large sandstone blocks at the base of the small cliff sometimes have three toed footprints on the surface; the footprint bed is the layer of sandstone about 3 to 4 metres up the cliff face from which these blocks have fallen; although Burniston Bay is the easiest place to find the footprints, they can be found all along the coast from Scarborough to Whitby.
Marine Reptiles: During the Jurassic period the seas in this part of the world were the home of ichthyosaurs and plesiosaurs; both measured from 3 to 13 metres in length; the ichthyosaur resembled a dolphin in appearance and is thought to have been a fast and powerful swimmer; the ichthyosaur was the only marine reptile known to give birth to live young; the plesiosaur had a very long neck and used four paddle like fins for propulsion; in contrast to the ichthyosaur, the plesiosaur would leave the water to lay eggs on the land; it is thought that if the Loch Ness Monster exists it is probably a descendent of the plesiosaur; both reptiles were air breathers and would have to surface regularly for air. Although fossilised remains of reptiles are uncommon they can be found in this area; vertebrae are the most common parts to be found, usually on the seashore and look like discs with concave sides ranging from 1cm to 30cm in diameter; complete skeletons are still occasionally found in the cliffs but are extremely difficult to remove intact.
Bivalves: Cockles, mussels and oysters are all bivalves; the only difference is that some of the shellfish you find on the Yorkshire Coast are 150 to 190 million years old; when shellfish died most of the shells became filled with mud or silt, this provided a solid core for the shell as it became fossilised; as the shell was made of a substance similar to the fossilising minerals quite often parts of the shell remain intact and the original colours are visible.
Crinoids: Amongst the shingle on the beach you may find very small fossils which resemble starfish, they are part of a crinoid, a creature which is related to the starfish; crinoid can be described as rather like a starfish on a stem; the stem would be made up of hundreds of these flat star shaped plates, called ossicles, stacked one on top of the other; at the top of the stem would be the head 'calyx' with 5 or more arms which were used to catch food and at the bottom of the stem a 'root' system to hold the creature down; although crinoids look like plants and have the nickname 'sea lillies' they are not plants.
Scaphopods: Scaphopods are shellfish which first put in an appearance in Devonian times, about 417 to 354 Million Years Ago, and have hardly changed since; they can still be found in warmer climates and are known as 'tusk shells' because of their similarity in appearance to elephant's tusks; in life a scaphopod lives buried in sand with just the thin end of the shell protruding into the water and the head end, called the foot, at the lower end.
Plant Remains: Plant remains are quite common in the Whitby and Scarborough areas; leaves are usually preserved as carbon impressions of the original leaf; tree trunks and branches are sometimes preserved as flattened coal like bands, sometimes as mineralised casts and occasionally as Jet.

Warning - Danger: There are significant risks with fossil hunting on the coast section to the west of Staithes harbour, so please be careful; some of the best places to look are at the foot of the cliffs, which are mostly vertical or nearly vertical, and contain much unstable shaley material, so there is a slight danger of rock falls; also the area is reached by the mid tide, so fossil hunting can only be performed in safety on a falling tide; the foot of the cliffs should always be approached with care; the rock platform can be extremely slippery with algae, especially immediately to the west of Staithes harbour wall; adequate clothing, a rucksack and a hard hat should be worn whilst fossil hunting, in order to reduce the chance of an injury. Cleveland Ironstone Works: Attempts have been made to work parts of the Cleveland Ironstone Formation from the coastal exposures in the 19th century but they were unsuccessful apparently because of the poor selection of ore and contamination; working of the Domerian ironstone began at Grosmont in 1839 and continued there until about 1892; the Main Seam was worked at Skinningrove in 1848 and in the Eston Hills in 1851; from this time onwards Jurassic ore production exceeded that from the Carboniferous. Transport to the blast furnaces of the growing Teesside towns was easy and short and iron ore production soared; by 1870 more than 4 million tons of ore were raised annually in Cleveland, which increased to 6 million tons by 1875 and this massive production dominated British bedded ore production for almost fifty years. Exploitation of the Main Seam moved progressively southward but there was a steady southward deterioration in the iron content; this also increased haulage distances to the iron works and production diminished to less than half after 1920 and ceased atogether in 1964, leaving untouched reserves of about 232 million tons in the Cleveland area. Of the iron rich minerals in the ore pure siderite contains 48.2 per cent metallic iron while chamosite contains about 32 per cent; variations in the proportions of the various minerals across the ore field are clearly important; the proportion of clastic material such as quartz sand is another variable; the cliff section at Staithes consists mainly of shale but with ironstone beds or "seams" at intervals; evidence of past mining can be seen at Old Nab.