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Tertiary (65Ma-2.5Ma)



The Tertiary Period began 65 million years ago with fire, and ended a little over 2.5 million years ago in ice. It opened with a meteorite, around 10km across, slamming into the Earth with unimaginable force at the Chicxulub impact site close to Mexico. This catastrophic event marks the close of the preceding Cretaceous Period and dealt the final blow to an already-declining population of dinosaurs, along with other Mesozoic creatures such as ammonites and belemnites. After a period in excess of 62 million years, the Tertiary came to a close when a large part of both planetary hemispheres were overwhelmed by advancing glaciers marking the onset of the succeeding Quaternary Period.

This shaded relief image of Mexico's Yucatan Peninsula show a subtle, but unmistakable, indication of the Chicxulub impact crater. Most scientists now agree that this impact was the cause of the Cretatious-Tertiary Extinction, the event 65 million years ago that marked the sudden extinction of the dinosaurs as well as the majority of life then on Earth.

Tertiary Rock in the Tees Valley

No sedimentary rocks of Tertiary age exist within the Tees Valley today, but the district’s single example of a native igneous rock, the Cleveland Dyke, was emplaced during the Tertiary Period some 58 million years ago. Intense volcanic activity along the west coast of Scotland caused the Earth’s crust to become stretched as the Atlantic Ocean grew between the continents of North America and Europe. Molten rock (magma) was injected into fissures deep beneath the surface. On cooling, emplaced magma formed dykes which can today be found at, or close to, the surface. One of these extends all the way from the Isle of Mull, through Teesside, and terminates on the North York Moors. A distance of 260 miles.

Whinstone Mine

An idealised cutaway showing the working of whinstone by both quarry and mine.

The magma formed a durable, blue-grey rock, a type of dolerite known coloquially as whinstone, much used for road metal and cobbles. It was extensively quarried and mined between 1869 and the 1930s at Cliff Rigg, near Great Ayton under leases with Leeds City Council, as well as at Preston-on-Tees, Ingleby Barwick, and numerous sites across the North York Moors.

The Tertiary period also saw evolution of our human ancestors including Homo habilis (Handy Man), the first tool user, a species that wandered the African plains between 1.9 million to 1.6 million years ago. Homo sapiens (Wise or Knowing Man), like you and I, did not appear until a mere 200,000 years ago, and geology as a science is said not have really got going until the late 1700s.

However, could it be that their expertise in the production and use of intricate stone tools qualify our primitive ancestors to be looked upon as the world’s first real geologists?

If you have a question about your local geology, or a rock, mineral or fossil you’d like identified then please visit our Contact Us page and we will do our best to help.


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Huntcliff-at-Saltburn Kilton Mine from Little Moorsholm Kilton Mine Spoil Heap Loftus Alum Quarry Redcar Submerged Forest Roseberry Topping Skinningrove Blast Furnaces Spa Wood Ironstone Mine View east from Boulby Quarries View north from Skelton View north-east from Loftus Quarries

Explore TVRIGS



One fundamental aspect of work done by Tees Valley RIGS Group involves compiling a Catalogue of Geodiversity which covers our area of operation - Geodiversity being the variety of rocks, fossils and unconsolidated deposits making up the district.



The area covered by TVRIGS, that is roughly much of ancient Cleveland and includes the northern parts of the North Yorkshire Moors, has a varied geology with rocks exposed at surface ranging in age from the Upper Carboniferous, ...



Part of the fun of geology is making visits to sites of interest, where the geology, industrial archaeology, or both can be seen in-the-flesh as it were. To help people get the most out of such visits TVRIGS has compiled a number of outings (geotrails) ...

marske quarry


As a body of volunteers Tees Valley RIGS Group receives no direct funding but can bid for small amounts from funding bodies such as HLF (Heritage Lottery Fund), ALSF (Aggregates Levy Sustainability Fund), and so on when such monies are ...