Geological Heritage Sites

Published 27.10.2024Abstracts

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Geological Heritage Sites are key places with extraordinary geological elements or processes of the highest scientific relevance. They are used as a global reference, and/or with a substantial contribution to the development of geological sciences through history.

What is this?

The sites are promoted by the International Union of Geological Sciences (IUGS). This organisation was founded in 1961. It has 121 national members, representing over a million geoscientists, and is in fact one of the World’s largest scientific organisations. 

In 2022 the organisation’s International Commission on Geoheritage (ICG) published a collection of 100 heritage sites. In 2024 there was a follow-up with 100 more. The plan is to publish another 100 in 2026.

The aim is to give visibility to those sites. It identifies them as being of the highest scientific value. Moreover, the IUGS/ICG state that the sites served to develop the science of geology, particularly its early history. They are the world’s best demonstrations of geologic features and processes. They are also sites of fabulous discoveries of the Earth and its history.

IUGS First and Second 100 Sites Books
IUGS First and Second 100 Sites Books

Sandalsand has been to 19 of the 200 sites. I will here with my own pictures and with short descriptions partly derived from IUGS, present my collection. They may be viewed as representative samples of the full list, even though some categories are empty. IUGS has split their 200 sites into nine categories.

IUGS publications on this subject, see bottom, are unfortunately not written for the laymen amongst us. Therefore, I have tried to translate the text in the categories into a more comprehensible language by using a variety of other sources.

Click the images to expand.

1. History of Geosciences

The reconnaissance of geosites of historical relevance is of great importance, as it allows us to recognize the foundation, the development and consequently the scientific potential of the geological sciences, as well as their role in human society.

25 of the geological heritage sites belong to this category. Sandalsand has visited two of them.

5 The Paleocene volcanic rocks of the Giant’s Causeway and Causeway coast: One of the best examples of columnar basalt in the world. It is a key site in proving the origin of extrusive igneous rocks dating back to the 18th century. United Kingdom. This is also a UNESCO World Heritage Site.

113 Esmark Moraine and Otto Tank’s Moraine: The sites where Jens Esmark discovered the ice age in 1823. Norway. The ice ages have covered parts of the Earth several times, but it was not until Esmark visited two moraines that someone came up with the idea that there had actually been ice ages, and that they had shaped the landscape below the ice cap.

2. Stratigraphy and sedimentology

Stratigraphy is a branch of geology concerned with the study of rock layers (strata) and layering (stratification). It is primarily used in the study of sedimentary and layered volcanic rocks. Sedimentology, the study of sedimentary rocks and the processes by which they are formed, includes and is related to a large number of phenomena. Sedimentology includes the five fundamental processes defined by the term sediaentation –weathering, erosion, transportation, deposition and diagenesis.

IUGS have 29 geological heritage sites in this category. Here are five of them.

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118 Carboniferous evolution of The Burren and Cliffs of Moher: One of the most complete sections with Mississippian limestones in exceptional karst landscapes and Pennsylvanian deltaic in spectacular sea cliffs. Contrary to the North American place names in the previous sentence, these cliffs are in Ireland. This is also a UNESCO Global Geopark.

123 The Oligocene-Miocene molassic and rock pinacles of Meteora: One of the most impressive molassic accumulations of the world with an iconic landscape of pinnacles and rock pillars formations. In geology, “molasse” are sandstones, shales and conglomerates that form as terrestrial or shallow marine deposits in front of rising mountain chains. Meteora is in Greece and is a UNESCO World Heritage Site and UNESCO Global Geopark as well. Sandalsand found, along with countless other visitors, the combination of rocks and monasteries perched on top of these rocks, extremely fascinating.

125 Etosha Pan: One of the largest paleolake salt pans in the world, which supported a diverse Neogene to Pleistocene fossil fauna. Namibia. This is also home to fascinating wildlife even today. The 120-kilometre-long dry lakebed and its surroundings are protected as Namibia’s second-largest wildlife park. The pan is mostly dry but after heavy rains it is flooded with a thin layer of water, which is heavily salted by the mineral deposits on the surface.

129 Uyuni salt flat: The world’s largest and highest extensive evaporitic deposit with the greatest reserves of lithium brines. It covers an area of 10,582 square kilometres in Bolivia, near the crest of the Andes at an elevation of 3,656 m.

130 The Dead Sea: The Dead Sea is an excellent site for observing geomorphological, sedimentological, lacustrine, and geochemical processes and studying tectonics and paleoclimate. Israel; Jordan. This lake, or inland sea as it is salty, lies actually 430 metres below sea level.

3. Paleontology

This is the scientific study of life of the geologic past that involves the analysis of plant and animal fossils, including those of microscopic size, preserved in rocks.

Sandalsand has not been to any of the 33 sites that fall into this category.

4. Igneous and metamorphic petrology

Igneous petrology involves the study of the origin and nature of magma. It also involves the identification, classification, origin, evolution, and processes of formation and crystallisation of igneous rocks. Metamorphic petrology is the study of metamorphic rocks, which are rocks that have been transformed from one rock type into another through the action of heat, pressure, and chemically active fluids.

16 of IUGS’ 200 sites fall into this category. Sandalsand has been to one.

150 The Cambrian Leka Ophiolite: One of the best exposed and accessible Caledonian ophiolite complexes showing the remnants of the Iapetus Ocean. Norway. This is in addition a UNESCO Global Geopark. So what was this Iapetus Ocean? Well, it existed between 600 and 400 million years ago. An ophiolite is a section of Earth’s oceanic crust and the underlying upper mantle that has been uplifted and exposed, and often emplaced onto continental crustal rocks.

5. Volcanology

Volcanology deals with the formation, distribution, and classification of volcanoes as well as with their structure and the kinds of materials ejected during an eruption (such as pyroclastic flows, lava, dust, ash, and volcanic gases).

There are 27 sites in this category of which Sandalsand has been to two.

62 The Quaternary Santorini Caldera: One of the largest calderas in the Mediterranean Sea formed by Plinian eruptions in a volcanic arc tectonic framework. Greece. The cliffs of Santorini at Thera, offer spectacular views of the caldera. In touristic brochures and popular belief, this is what may have been the origin of the fictional Atlantis island mentioned by Plato.

65 The Miocene Cappadocian Ignimbrites sequence: IUGS describes this as voluminous eruption deposits in a fluviolacustrine sequence with ‘fairy-chimney’ development produced by uplift and erosion. Türkiye. This fairy-tale landscape on the Anatolian plateau in central Türkiye is also a UNESCO World Heritage Site for both its cultural and natural heritage.

6. Tectonics

This is the scientific study of the deformation of the rocks that make up the Earth’s crust and the forces that produce such deformation. It deals with the folding and faulting associated with mountain building; the large-scale, gradual upward and downward movements of the crust (epeirogenic movements); and also sudden horizontal displacements along faults. 

There are 18 sites of this category.

164 The Mid-Atlantic ridge on Reykjanes: Active rift zone onshore with faulting, fissure eruptions, hyaloclastite ridges and a geothermal area. Iceland. There have actually been active eruptions quite recently in this area and the famous Blue Lagoon had to close for a period. This is also a UNESCO Global Geopark.

7. Mineralogy

A scientific discipline that is concerned with all aspects of minerals, including their physical properties, chemical composition, internal crystal structure, and occurrence and distribution in nature and their origins in terms of the physicochemical conditions of formation.

Sandalsand has not been to any of the 33 sites that fall into this category.

8. Geomorphology and active geological processes

Scientific discipline concerned with the description and classification of the Earth’s topographic features.

There are 39 sites on the IUGS list of geological heritage sites. Sandalsand’s collection consists of these eight.

79 The Sugar Loaf monolith of Rio de Janeiro: One of the most iconic rock monoliths in the world in an urban landscape. Brazil. This rock has wonderful beaches on either side and is a UNESCO World Heritage Site.

80 Shilin Karst: The best site worldwide preserving and displaying various pinnacle karst landforms. China. This amazing landscape is figured on two other lists as well, the UNESCO World Heritage Site and the UNESCO Global Geopark list.

86 Mosi-oa-Tunya/Victoria Falls: The “the smoke that thunders” forming the largest sheet of falling water in the world. Zambia; Zimbabwe. One of the world’s most famous waterfalls is also a UNESCO World Heritage Site.

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88 Jutulhogget Canyon: A large canyon created by a dramatic ice age flood. Norway. This is the second Norwegian contribution to the list that is related to the ice age. See also no. 113 above.

91 The Okavango Delta: Africa’s largest inland alluvial fan and an exceptional example of the interaction between climatic, hydrological and biological processes. Botswana. In addition, this is a UNESCO World Heritage Site.

93 Namib Sand Sea: The highest diversity of dune types in a coastal desert influenced by fog. Namibia. The huge sand mountains starts inland and ends in the Atlantic Ocean. This is another UNESCO World Heritage Site.

96 Pamukkale Travertines: A globally outstanding type site with a high diversity of travertine features and processes on an active fault. Türkiye. The steps are on the UNESCO World Heritage List.

190 Guilin Karst: A global reference to show the geological and geomorphological effects of continental karst development. China. Finally, this is yet another UNESCO World Heritage Site.

9. Impact structures and extraterrestrial rocks

This category contains geological structures created when extraterrestrial objects such as asteroids and comets impact Earth’s surface. Impact structures range from small craters (just a few meters in diameter) to massive basins hundreds of kilometres across.

Sandalsand has not been to any of the 5 sites that fall into this category.

Read more

Read about the geological heritage sites on the IUGS website and download their publications for free. They are great to read on screen or if you like, you can order them as coffee-table books. There is a slight problem though, which I indicated above; they are written by geoscientists for geoscientists. Nonetheless, they have great pictures and represent very fine introductions to the evolution of this planet.

54 of the IUGS sites are UNESCO World Heritage Sites as well, and 36 are UNESCO Global Geoparks.

Here on Sandalsand you can read up on the World Heritage Sites and the large number this author has visited. This article is part of a category I have called “Abstracts of the World“. Click to find more abstracts.