The geological history of the Hague

2.1 billion years of history

La Hague is home to an exceptional geological heritage. This very small territory, barely 150 km², allows us to delve into 2.1 billion years of Earth's history, that is to say, to observe the oldest rocks in metropolitan France and to tell half of the history of our Planet.

It contains the remains of three ancient mountain ranges: the Icartian range (dated at 2 billion years old), the Cadomian range (between 650 and 540 million years old) and the Variscan (or Hercynian; built about 300 million years ago).

The sedimentary deposits that make up some of its live cliffs also allow us to appreciate the fluctuations in sea level and the climatic changes of the last 200,000 years.

Major geological sites

Within the La Hague Geopark, 37 sites of geological interest have been selected to provide a deeper understanding of Earth's history and the resulting challenges in terms of ecosystem preservation, sustainable development, and resilience to natural hazards. Illustrating 12 geological periods, these sites represent a wide range of topics (magmatism, metamorphism, sedimentology, paleontology, geomorphology, volcanology, etc.) and help us understand how three successive orogenies and Quaternary climatic variations are responsible for the diversity of today's landscapes, the richness of local building materials, and the varying degrees of vulnerability of the La Hague coast to climate change. The La Hague Geopark thus offers a holistic and educational approach to the consequences of this geological history on other aspects of heritage and allows us to draw parallels with phenomena occurring elsewhere in the world.

Because some sites are easier to understand than others, and to take into account their respective access conditions and vulnerabilities, they do not all benefit from the same level of valuation today.

Some examples of geological sites in the La Hague Geopark

Castel Vendon geosite

Icartian Chain

Made famous by Jean-François Millet, this site is also a geological monument; it is an augen gneiss whose original granite is dated to 2.1 billion years ago

Geosite of the Pointe de Jardeheu

Cadomian chain 

Beneath the Jardeheu semaphore and on the foreshore to the east, various types of ancient igneous rocks intruded into the Icartian gneisses are exposed. A fairly light-colored, black and white diorite stands out, dated to around 610 million years ago, placing it at the beginning of the Cadomian cycle. (Photo: Cotentin Drone Studio)

Ecuty Bay Geosite

Cadomian chain 

The Monzonite of Anse St Martin is unique in that it contains dark enclaves corresponding to fragments of magma from mantle melting that were brought to the surface along with its own magma. This rock is dated at 580 Ma. (Photo: Yohann Poprawski)

Ecuty Bay Geosite

Cadomian chain

When the sea recedes, the rocky foreshore of Ecuty Bay reveals a diversity of metamorphic and igneous rocks. The pink granite, in particular, gives the bay its color. Dated to 570 million years ago, it marks the end of the Cadomian period. (Photo: Yohann Poprawski)

Geosite of the Omonville stone quarry

Cadomian chain

This family-run business, with restricted access, quarries Cambrian arkose and conglomerates formed by the erosion of the Cadomian mountain range. These rocks consist of alternating layers of fine and coarser material. Characterized by a grey/beige color, they are found in many buildings on the peninsula.

Geosite of Vauville's career

Variscan chain

Currents and waves have left their imprints on this ancient seabed, dated to 470 million years ago and known as the May sandstone. The Variscan orogeny, formed between 360 and 300 million years ago, subsequently overturned it. (Photo: Arnaud Guérin – Lithospère)

Cap de La Hague Geosite

Variscan chain

The foreshore near the La Hague semaphore station reveals two types of veins injected into the Cadomian granite of Auderville: (1) dolerite veins (dark-colored rock) to the east, attributed to the beginning of the Variscan orogeny; (2) lamprophyre veins (brownish tint) to the west, linked to the collapse of the Variscan orogeny. (Photo: Arnaud Guérin – Lithosphère)

Herquemoulin Geosite

Quaternary

Walls of headland form the cliffs along the entire bay. This accumulation of rocky material bears witness to the alternating glacial and interglacial periods that prevailed in Northwest Europe during the Quaternary period. (Photo: Arnaud Guérin – Lithosphère)

Geosite of the Pointe de Jardeheu

Quaternary

This site reveals, in its micro-cliff, traces of a perched beach dating from the Eemian period, between 130,000 and 115,000 years ago. Affected by cryoturbation during the Weichselian period, which uplifted the pebbles almost vertically, it was located at a higher altitude than the current sea level. (Photo: Arnaud Guérin – Lithosphère)

Geosite of the La Hague dunes

Quaternary

20,000 years ago, the land where the dunes now stand was composed of hills of Beaumont schist and May sandstone. At their base lay a wetland. As the climate warmed during the last 6 and 7 millennia, the sea level rose, pushing significant quantities of sand ahead of it. Thanks to frequent west/southwest winds, this sand covered the wetland and then the hills.

The mineral tale of a planet in motion

This educational documentary film tells the geological story of La Hague within the broader context of Earth's history. It is shown continuously at the Tourp, the La Hague visitor center.