North York Moors

North York Moors logo
Browse section

Geology

Cliffs at Runswick BayCliffs at Runswick Bay

The varied landscapes of the National Park owe much of their appearance to the underlying geology, the result of over 200 million years of Earth history. This is a period that has seen North Yorkshire flooded by oceans, covered in huge river deltas and – most recently (20,000 years ago) – invaded by great ice sheets. 

It is these events, and the evidence they have left behind, that has brought geologists to the area since the science began, starting with William Smith (1769–1839), known as 'the ‘Father of English geology', who created the first geological map of Britain. The museum he founded in Scarborough, the Rotunda Museum, is still first port of call for anyone fascinated by the local geology.

Today, geologists travel from all over the world to study the rocks of the North York Moors. The area is particularly famous for its fossil remains and dinosaur footprints, each telling a story from times when North Yorkshire looked very different.

Many locations also bear the scars of human exploitation of the many resources contained within the rocks of the North York Moors. The mining and quarrying of ironstone, alum, coal, building stone and jet have all left tell-tale signs and have had a significant impact on local history and heritage. 

The way the landscape looks today – and how we use it and enjoy it – is entirely down to how it was made and how it has been modified since. 

A brief geological history

Our coastline is often called the ‘Dinosaur Coast’ because of the sheer number and quality of the dinosaur footprints and fossils discovered here. In fact, it’s no exaggeration to say that this is ‘Jurassic Park’. Most of the rocks in the North York Moors were formed between 200 and 145 million years ago – the Jurassic Period. 

Lower Jurassic

The oldest rocks within the National Park are Lower Jurassic, 200 million years old. These are the dark-coloured shales and limestones that can be seen along the coast at places such as Robin Hood's Bay, and from Whitby north to Saltburn.

Middle Jurassic

By around 170 million years ago, in the Middle Jurassic period, the sea level had fallen and the area was covered in great river channels and swamps. These conditions formed the thick sandstones that outcrop along the coast above the Lower Jurassic shales, and which form the bedrock of the central moorland

Upper Jurassic

The Upper Jurassic, around 150 million years ago, saw the return of the ocean to the area as sea levels rose. These waters deposited the limestone that forms the Tabular Hills

Ice Age

During the last Ice Age, which peaked around 20,000 years ago, the area was bordered by ice sheets, often hundreds of metres thick. Glacial lakes and meltwater broke through low points in the landscape, carving deep, steep-sided valleys such as Newtondale and Forge Valley.