{"id":38032,"date":"2020-06-09T06:57:51","date_gmt":"2020-06-09T06:57:51","guid":{"rendered":"https:\/\/www.bgs.ac.uk\/?page_id=38032"},"modified":"2021-06-09T13:19:59","modified_gmt":"2021-06-09T13:19:59","slug":"sinkholes","status":"publish","type":"page","link":"https:\/\/www.bgs.ac.uk\/discovering-geology\/earth-hazards\/sinkholes\/","title":{"rendered":"Understanding sinkholes and karst"},"content":{"rendered":"\t\t\t<section class=\"hero-section hero-section-with-social\">\n\t\t\t\t\t\t\t\t<div class=\"hero-info-wrap\">\n\t\t\t\t\t<div class=\"container\">\n\t\t\t\t\t\t<div class=\"row\">\n\t\t\t\t\t\t\t<div class=\"col-12\">\n\t\t\t\t\t\t\t\t<div class=\"hero-info\">\n\t\t\t\t\t\t\t\t\t<h1>Understanding sinkholes and karst<\/h1>\n\t\t\t\t\t\t\t\t\t<p>Discovering Geology &mdash; Earth hazards<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t\t\t\t<\/div>\n\t\t\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t\t\t\t\n\t\t\t<div class=\"social-wrap social-wrap-inline-them\">\n\t\t\t\t<div class=\"sea-background-f\">\n\t\t\t\t\t<span>Share this article<\/span><a target=\"_blank\"  href=\"https:\/\/www.facebook.com\/sharer\/sharer.php?u=https:\/\/www.bgs.ac.uk\/discovering-geology\/earth-hazards\/sinkholes\/\"><span class=\"icon-facebook\"><span class=\"hidden\">Facebook<\/span><\/span><\/a><a target=\"_blank\"  href=\"https:\/\/twitter.com\/intent\/tweet?text=Understanding%20sinkholes%20and%20karst&#038;url=https:\/\/www.bgs.ac.uk\/discovering-geology\/earth-hazards\/sinkholes\/\"><span class=\"icon-twitter\"><span class=\"hidden\">Twitter<\/span><\/span><\/a><a   onclick=\"javascript:void( (function() {var e=document.createElement('script' );e.setAttribute('type','text\/javascript' );e.setAttribute('charset','UTF-8' );e.setAttribute('src','\/\/assets.pinterest.com\/js\/pinmarklet.js?r='+Math.random()*99999999);document.body.appendChild(e)})());\"  href=\"javascript:void(0);\"><span class=\"icon-pinterest\"><span class=\"hidden\">Pinterest<\/span><\/span><\/a><a target=\"_blank\"  href=\"https:\/\/wa.me?text=https:\/\/www.bgs.ac.uk\/discovering-geology\/earth-hazards\/sinkholes\/\"><span class=\"icon-whatsapp\"><span class=\"hidden\">WhatsApp<\/span><\/span><\/a><a   href=\"mailto:?subject=Understanding%20sinkholes%20and%20karst&#038;body=Sinkholes%20are%20hollows%20that%20are%20the%20result%20of%20some%20kind%20of%20collapse%20of%20an%20underlying%20layer%20of%20rock.%20(https:\/\/www.bgs.ac.uk\/discovering-geology\/earth-hazards\/sinkholes\/)\"><span class=\"icon-mail\"><span class=\"hidden\">Email<\/span><\/span><\/a><a href=\"#\" data-copy=\"https:\/\/www.bgs.ac.uk\/discovering-geology\/earth-hazards\/sinkholes\/\" class=\"copy-url-on-click\"><span class=\"icon-link\"><span class=\"hidden\">Copy Link<\/span><\/span><\/a><\/div><\/div>\t\t\t\t\t\t\t<\/section>\n\t\t\t\n\n\n<section class=\"wp-block-bgs-blocks-content-container content-section\"><div class=\"container\"><div class=\"row\"><div class=\"col-12\">\n<p>Sinkholes are often saucer-shaped hollows that are the result of some kind of collapse or removal of an underlying layer of rocks that used to support the layer of material at the surface. However, sinkholes can appear in a variety of different shapes and settings depending on the composition of the rocks and different interacting processes.<\/p>\n\n\n\n<p>Research at BGS extends beyond the distribution and processes associated with sinkhole formation to the broader subject of karst, which is the geomorphological term applied to the landscape that results from the dissolution of soluble rocks, e.g. the characteristic limestone pavements of the Pennines.<\/p>\n\n\n\n<ul><li><a href=\"#appearance\">Sinkhole appearance<\/a><\/li><li><a href=\"#triggers\">What triggers sinkholes?<\/a><\/li><li><a href=\"#types\">Types of sinkholes<\/a><\/li><li><a href=\"#karst\">Where does karst occur in the UK?<\/a><\/li><li><a href=\"#sinkholes\">Where do sinkholes occur in the UK?<\/a><\/li><\/ul>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"appearance\">Sinkhole appearance<\/h2>\n\n\n\n<p>Some sinkholes result from the removal of a soluble rock such as chalk, gypsum or limestone. These are called solution sinkholes. These rocks dissolve when attacked by rainfall or groundwater that is acidic. Solution sinkholes have sides that vary from gentle slopes to almost vertical, while their shapes include saucer-like hollows, cones, cylindrical potholes and shafts.<\/p>\n\n\n\n<p>Streams or rivers may enter a sinkhole and disappear underground. This type of sinkhole is often called a swallow hole.<\/p>\n\n\n\t\t\t\t<div  id=\"video-7820-block_5edf85d00244a\" class=\"video-wrap  \" >\n\t\t\t\t\t<div class=\"img-wrap\">\n\t\t\t\t\t\t<div class=\"position-relative\">\n\t\t\t\t\t\t\t<img decoding=\"async\" class=\"\" src=\"https:\/\/i3.ytimg.com\/vi\/6jWyHE3X9Uc\/hqdefault.jpg\" \/>\t\t\t\t\t\t\t<img decoding=\"async\" src=\"https:\/\/www.bgs.ac.uk\/wp-content\/themes\/bgs\/img\/video.svg\" class=\"video-play\">\n\t\t\t\t\t\t<\/div>\n\t\t\t\t\t\t\t\t\t\t\t\t<div class=\"caption sm-line\">\n\t\t\t\t\t\t\t<div class=\"caption-icon\">\n\t\t\t\t\t\t\t\t<img decoding=\"async\" src=\"https:\/\/www.bgs.ac.uk\/wp-content\/themes\/bgs\/img\/info-caption.svg\" alt=\"Information icon\">\n\t\t\t\t\t\t\t<\/div>\n\t\t\t\t\t\t\t<div class=\"caption-text\"><p>Soluble rocks such as salt, gypsum, chalk and limestone can be dissolved by groundwater on a local scale, causing the collapse of the overlying ground. This collapse is called a sinkhole. In this model, the white area labelled soluble rock is salt. As the water filters down through the rocks above, the salt starts to dissolve and the rocks above drop down to form a sinkhole. BGS \u00a9UKRI.<\/p>\n<\/div>\n\t\t\t\t\t\t<\/div>\n\t\t\t\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t\t<div class=\"into-video\">\n\t\t\t\t\t\t<noscript>\n\t\t\t\t\t\t\t<iframe class=\"video-section\" src=\"https:\/\/youtube.com\/embed\/6jWyHE3X9Uc?enablejsapi=1&#038;version=3&#038;playerapiid=ytplayer&#038;rel=0&#038;autoplay=1\" frameborder=\"0\" allow=\"accelerometer; autoplay; encrypted-media; gyroscope; picture-in-picture\" allowfullscreen><\/iframe>\t\t\t\t\t\t<\/noscript>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\n\n\n<p>Although a natural process, the formation of sinkholes is often accelerated or triggered by human influences, such as broken drains, water mains and sewerage pipes, or modified drainage and diverted surface water; these wash sediment into the underlying materials, causing subsidence.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"triggers\">What triggers sinkholes?<\/h2>\n\n\n\n<p>Sinkholes can occur rapidly and apparently without warning. It is therefore important to consider the potential for sinkholes during planning (hazard susceptibility studies) and characterise them so that people can mitigate associated risks. <\/p>\n\n\n\n<p>Several processes can trigger sinkholes. Whilst the process of gradual dissolution can cause a sinkhole to form at the surface, other factors, including human activity, can induce sinkholes to form.<\/p>\n\n\n<div  class=\"accordions\">\n\t\t\t\t<div class=\"acc-wrap\">\n\t\t\t\t\t<button class=\"acc-top secondary-background icon-arrow button no-btn\"><span class=\"button-content\" tabindex=\"-1\">Heavy rain and flooding<\/span><\/button>\n\t\t\t\t\t<div class=\"acc-body sea-background-e\">\n\t\t\t\t\t\t<p>Heavy rain or surface flooding can initiate the collapse of normally stable cavities, especially those developed within\u00a0<a href=\"https:\/\/www.bgs.ac.uk\/datasets\/bgs-geology\/bgs-geology-themes\/#superficial\">superficial deposits<\/a>.<\/p>\n\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t<\/div><div  class=\"accordions\">\n\t\t\t\t<div class=\"acc-wrap\">\n\t\t\t\t\t<button class=\"acc-top secondary-background icon-arrow button no-btn\"><span class=\"button-content\" tabindex=\"-1\">Water leaks<\/span><\/button>\n\t\t\t\t\t<div class=\"acc-body sea-background-e\">\n\t\t\t\t\t\t<p>Leaking drainage pipes, burst water mains, irrigation or even the act of emptying a swimming pool are all documented examples of sinkhole triggers.<\/p>\n\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t<\/div><div  class=\"accordions\">\n\t\t\t\t<div class=\"acc-wrap\">\n\t\t\t\t\t<button class=\"acc-top secondary-background icon-arrow button no-btn\"><span class=\"button-content\" tabindex=\"-1\">Building works<\/span><\/button>\n\t\t\t\t\t<div class=\"acc-body sea-background-e\">\n\t\t\t\t\t\t<p>Construction and development are also potential triggers. Modifying surface drainage or altering the loads imposed on the ground without adequate support can caused sinkholes to develop.<\/p>\n\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t<\/div><div  class=\"accordions\">\n\t\t\t\t<div class=\"acc-wrap\">\n\t\t\t\t\t<button class=\"acc-top secondary-background icon-arrow button no-btn\"><span class=\"button-content\" tabindex=\"-1\">Changes in water table level\u00a0<\/span><\/button>\n\t\t\t\t\t<div class=\"acc-body sea-background-e\">\n\t\t\t\t\t\t<p>Drought or groundwater abstraction can cause sinkholes by changing the level of the water table. This removes the buoyant support that groundwater provides to a cavity. Draining these cavities can cause them to collapse.<\/p>\n\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t<\/div><div  class=\"accordions\">\n\t\t\t\t<div class=\"acc-wrap\">\n\t\t\t\t\t<button class=\"acc-top secondary-background icon-arrow button no-btn\"><span class=\"button-content\" tabindex=\"-1\">Mining<\/span><\/button>\n\t\t\t\t\t<div class=\"acc-body sea-background-e\">\n\t\t\t\t\t\t<p>Mining can be a factor in causing sinkholes, either by dewatering and lowering of the water table, or by intercepting clay-filled voids that subsequently collapse. Several sinkholes in Norwich have been caused by old chalk mines intercepting otherwise stable, sediment-filled voids.<\/p>\n\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t<\/div>\n\n\n<h2 class=\"wp-block-heading\" id=\"types\">Types of sinkhole<\/h2>\n\n\n\n<p>Sinkholes are classified in accordance with their formational processes. The rate at which they form is guided by the size of openings though which fluids flow, the head that is driving the flow system and the geochemistry. \u00a0For example, limestone rocks dissolve when attacked by rainfall or groundwater that is acidic.<\/p>\n\n\n<div  class=\"accordions\">\n\t\t\t\t<div class=\"acc-wrap\">\n\t\t\t\t\t<button class=\"acc-top secondary-background icon-arrow button no-btn\"><span class=\"button-content\" tabindex=\"-1\">Solution sinkholes<\/span><\/button>\n\t\t\t\t\t<div class=\"acc-body sea-background-e\">\n\t\t\t\t\t\t<p>Solution sinkholes are formed by local chemical weathering of the rock, where water accumulates around a fissure or joint in the rock. This may be underneath the soil or on the ground surface. The hollow that is formed is drained of water through the fissure or joint, but not before it has dissolved some of the rock. The depression gradually gets enlarged.<\/p>\n<figure id=\"attachment_38207\" aria-describedby=\"caption-attachment-38207\" style=\"width: 690px\" class=\"wp-caption alignnone\"><img loading=\"lazy\" decoding=\"async\" class=\"size-full wp-image-38207\" src=\"https:\/\/www.bgs.ac.uk\/wp-content\/uploads\/2020\/06\/Solution_sinkhole_south_wales_website.jpg\" alt=\"Solution sinkhole, South Wales\" width=\"690\" height=\"690\" srcset=\"https:\/\/www.bgs.ac.uk\/wp-content\/uploads\/2020\/06\/Solution_sinkhole_south_wales_website.jpg 690w, https:\/\/www.bgs.ac.uk\/wp-content\/uploads\/2020\/06\/Solution_sinkhole_south_wales_website-150x150.jpg 150w\" sizes=\"(max-width: 690px) 100vw, 690px\" \/><figcaption id=\"caption-attachment-38207\" class=\"wp-caption-text\">Solution sinkhole on Mynydd Llangynidr, South Wales. The stream formed after a high rainfall event. BGS \u00a9UKRI.<\/figcaption><\/figure>\n<figure id=\"attachment_73836\" aria-describedby=\"caption-attachment-73836\" style=\"width: 517px\" class=\"wp-caption alignnone\"><img loading=\"lazy\" decoding=\"async\" class=\"size-full wp-image-73836\" src=\"https:\/\/www.bgs.ac.uk\/wp-content\/uploads\/2021\/06\/Solution_sinkhole-e1623241471830.jpg\" alt=\"A diagram of a solution sinkhole forming, showing enlargement of ractures by water, surface erosion and collapse of overlying rock into caves and fissures to form a sinkhole on the surface\" width=\"517\" height=\"320\" \/><figcaption id=\"caption-attachment-73836\" class=\"wp-caption-text\">Solution sinkholes are formed by local chemical weathering (surface corrosion) of rock where water accumulates around a fissure or joint in the rock. Adapted from Waltham et al., 2005.<\/figcaption><\/figure>\n\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t<\/div><div  class=\"accordions\">\n\t\t\t\t<div class=\"acc-wrap\">\n\t\t\t\t\t<button class=\"acc-top secondary-background icon-arrow button no-btn\"><span class=\"button-content\" tabindex=\"-1\">Collapse sinkhole<\/span><\/button>\n\t\t\t\t\t<div class=\"acc-body sea-background-e\">\n\t\t\t\t\t\t<p>Collapse sinkholes occur where the gradual collapse of a cave passage occurs and eventually causes subsidence at the surface level. The collapse may gradually propagate up through the overlying strata to cause subsidence at the surface. These sometimes extend up into rocks that are not themselves prone to dissolution, creating a \u2018caprock sinkhole\u2019.<\/p>\n<p>Sinkholes formed exclusively this way are quite rare, although many sinkholes are in part formed by collapse: chemical weathering in a solution sinkhole may cause a part of the wall to become unsupported and unstable, resulting in collapse. Sinkholes of this type are common in parts of South Wales, where sandstone rocks overlie cavernous limestone. Others may be buried by more recent deposits.<\/p>\n<figure id=\"attachment_73839\" aria-describedby=\"caption-attachment-73839\" style=\"width: 480px\" class=\"wp-caption alignnone\"><img loading=\"lazy\" decoding=\"async\" class=\"size-full wp-image-73839\" src=\"https:\/\/www.bgs.ac.uk\/wp-content\/uploads\/2021\/06\/Hull_Pot_-_geograph.org_.uk_-_220704.jpg\" alt=\"A large, rectangular depression in the ground with vertical walls of grey rock. There are green hills in the background and the floor of the depression and the land around it are covered in green grass.\" width=\"480\" height=\"640\" \/><figcaption id=\"caption-attachment-73839\" class=\"wp-caption-text\">Hull Pot is a collapse sinkhole in Yorkshire. Hull Pot Beck enters as a waterfall on the left after very heavy rain but most of the time enters lower down via fissures in the limestone. Hull Pot.\u00a0 \u00a9 John Illingworth \/ Hull Pot \/ <a href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/2.0\/\" target=\"_blank\" rel=\"noopener\">CC BY-SA 2.0<\/a>.<\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<p><iframe loading=\"lazy\" src=\"\/\/www.youtube.com\/embed\/i0Pe9l7qPoA\" width=\"560\" height=\"314\" allowfullscreen=\"allowfullscreen\" data-mce-fragment=\"1\"><\/iframe><\/p>\n<p>Collapse sinkhole formation: as the water filters down through the rocks above, the limestone starts to dissolve and the rocks above drop down to form a sinkhole. BGS \u00a9UKRI.<\/p>\n<figure id=\"attachment_73840\" aria-describedby=\"caption-attachment-73840\" style=\"width: 517px\" class=\"wp-caption alignnone\"><img loading=\"lazy\" decoding=\"async\" class=\"size-full wp-image-73840\" src=\"https:\/\/www.bgs.ac.uk\/wp-content\/uploads\/2021\/06\/Collapse_sinkhole.jpg\" alt=\"A diagram of a collapse sinkhole, showing blocks of rocks falling from the surface into a collapsed cave system\" width=\"517\" height=\"307\" \/><figcaption id=\"caption-attachment-73840\" class=\"wp-caption-text\">Collapse sinkholes occur where the gradual collapse of a cave passage occurs and eventually causes subsidence at the surface level. Adapted from Waltham et al., 2005.<\/figcaption><\/figure>\n\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t<\/div><div  class=\"accordions\">\n\t\t\t\t<div class=\"acc-wrap\">\n\t\t\t\t\t<button class=\"acc-top secondary-background icon-arrow button no-btn\"><span class=\"button-content\" tabindex=\"-1\">Suffosion sinkhole<\/span><\/button>\n\t\t\t\t\t<div class=\"acc-body sea-background-e\">\n\t\t\t\t\t\t<p>Suffosion sinkholes form where solution of the rock has created a depression on the bedrock surface, under a covering of soil. The unsupported soil subsides into the cavity and leaves a depression in the landscape. These are sometimes referred to as subsidence sinkholes and, in Yorkshire where they are particularly common, they are often known as &#8216;shake holes&#8217;.<\/p>\n<p>If the cover material is sandy, it will tend to gradually slump into the fissures. However, if the material is more cohesive, like clay, then the cavity can grow quite large before suddenly collapsing; this is termed a \u2018drop out\u2019 sinkhole. It is these more spectacular collapses (dropout) that sometimes hit the headlines, for example in the area of Ripon in Yorkshire.<\/p>\n<figure id=\"attachment_38210\" aria-describedby=\"caption-attachment-38210\" style=\"width: 666px\" class=\"wp-caption alignnone\"><img loading=\"lazy\" decoding=\"async\" class=\"size-full wp-image-38210\" src=\"https:\/\/www.bgs.ac.uk\/wp-content\/uploads\/2020\/06\/suffosion_sinkhole_great_scar_yorkshire_website.jpg\" alt=\"Suffosion sinkholes - Great Scar\" width=\"666\" height=\"345\" \/><figcaption id=\"caption-attachment-38210\" class=\"wp-caption-text\">Suffosion sinkholes at Great Scar, Yorkshire Dales. BGS \u00a9UKRI.<\/figcaption><\/figure>\n<p>The glacial tills of Malham Moor are pockmarked by suffosion sinkholes, between about 1 and 15\u00a0m across. Some still have soil and grass on the floor of the sinkhole, but in others the fissured limestone is exposed, the soil having been eroded away by the rain and washed down into the underground river system.<\/p>\n<div class=\"mceTemp\"><\/div>\n<figure id=\"attachment_73847\" aria-describedby=\"caption-attachment-73847\" style=\"width: 517px\" class=\"wp-caption alignnone\"><img loading=\"lazy\" decoding=\"async\" class=\"size-full wp-image-73847\" src=\"https:\/\/www.bgs.ac.uk\/wp-content\/uploads\/2021\/06\/Suffosion_sinkhole.jpg\" alt=\"A diagram of the formation of a suffosion sinkhole, where water is washing overlying soil into a fissure in the bedrock, creating a depression at the surface\" width=\"517\" height=\"315\" \/><figcaption id=\"caption-attachment-73847\" class=\"wp-caption-text\">Suffosion sinkholes form where dissolution of rock has created a depression on the bedrock surface, but under a covering of soil. Adapted from Waltham et al., 2005.<\/figcaption><\/figure>\n\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t<\/div>\n\n\n<h2 class=\"wp-block-heading\" id=\"karst\">Where does karst occur in the UK?<\/h2>\n\n\n\n<p>There are a number of soluble rocks across the UK that form karst. These include Devonian and Carboniferous limestones, Permian and Triassic halite and gypsum, and Jurassic and Cretaceous limestones and chalk. <\/p>\n\n\n<figure  class=\"img-wrap\"><a href=\"https:\/\/www.bgs.ac.uk\/wp-content\/uploads\/2020\/08\/Map_of_soluble_rocks.jpg\" data-toggle=\"lightbox\" data-footer=\"&lt;p&gt;Soluble rock types and their distribution in Great Britain. Based on the BGS 1:625\u00a0000 scale Bedrock Geology map of the UK. BGS \u00a9 UKRI.&lt;\/p&gt;\n\" data-gallery=\"gallery_88931\"><img decoding=\"async\" src=\"https:\/\/www.bgs.ac.uk\/wp-content\/uploads\/2020\/08\/Map_of_soluble_rocks-150x150.jpg\" class=\"lazy-blur\" alt=\"Map of soluble rocks in the UK\" data-src=\"https:\/\/www.bgs.ac.uk\/wp-content\/uploads\/2020\/08\/Map_of_soluble_rocks.jpg\" \/><\/a><figcaption class=\"caption \">\n\t\t\t\t\t<div class=\"caption-icon\">\n\t\t\t\t\t\t<img decoding=\"async\" src=\"https:\/\/www.bgs.ac.uk\/wp-content\/themes\/bgs\/img\/info-caption.svg\" alt=\"Information icon\">\n\t\t\t\t\t<\/div>\n\t\t\t\t\t<div class=\"caption-text\"><p>Soluble rock types and their distribution in Great Britain. Based on the BGS 1:625\u00a0000 scale Bedrock Geology map of the UK. BGS \u00a9 UKRI.<\/p>\n<\/div>\n\t\t\t\t\t<div class=\"expand-box expand-box-top\"><a href=\"https:\/\/www.bgs.ac.uk\/wp-content\/uploads\/2020\/08\/Map_of_soluble_rocks.jpg\" data-toggle=\"lightbox\" data-footer=\"&lt;p&gt;Soluble rock types and their distribution in Great Britain. Based on the BGS 1:625\u00a0000 scale Bedrock Geology map of the UK. BGS \u00a9 UKRI.&lt;\/p&gt;\n\" data-gallery=\"gallery_88931\"><img decoding=\"async\" src=\"https:\/\/www.bgs.ac.uk\/wp-content\/themes\/bgs\/img\/expand.svg\" alt=\"Expand icon\"><\/a><\/div>\n\t\t\t\t<\/figcaption><\/figure>\n\n\n<h2 class=\"wp-block-heading\" id=\"sinkholes\">Where do sinkholes occur in the UK?<\/h2>\n\n\n\n<p>Most sinkholes are relatively small or are in upland, rural locations. They include areas underlain by Carboniferous limestone, notably the Mendips, parts of Wales, the Peak District, and the northern Pennines including the Yorkshire Dales.<\/p>\n\n\n\n<p>The most susceptible area in the UK, however, is the Permian gypsum deposits of north-east England, particularly around <a href=\"https:\/\/www.bgs.ac.uk\/geology-projects\/sinkholes-research\/ripon-sinkhole-november-2016\/\">Ripon<\/a> and areas underlain by a similar geology. In Ripon, many large sinkholes have developed, some of which have affected property and infrastructure. This is because gypsum is far more soluble than limestone and so dissolves more rapidly.<\/p>\n\n\n\n<p>Sinkholes also occur over salt deposits, commonly in areas such as Cheshire where brine has been extracted, making it difficult to separate naturally formed sinkholes from those created by man.<\/p>\n\n\n\n<p>The Chalk Group is also susceptible and surface lowering of the Chalk is especially evident where it is covered by younger clay and sand deposits (such the \u2018Clay-with Flints\u2019 and Palaeogene strata), notably in parts of Dorset, Hampshire and the Chilterns. <\/p>\n\n\n\n<p>In Scotland, sinkholes are generally rare except in parts of Assynt underlain by the Cambrian Durness Limestone.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Reference<\/h2>\n\n\n<div  class=\"accordions\">\n\t\t\t\t<div class=\"acc-wrap\">\n\t\t\t\t\t<button class=\"acc-top secondary-background icon-arrow button no-btn\"><span class=\"button-content\" tabindex=\"-1\">Reference<\/span><\/button>\n\t\t\t\t\t<div class=\"acc-body sea-background-e\">\n\t\t\t\t\t\t<p><span class=\"authors-affiliations__name\">Waltham, T, <\/span><span class=\"authors-affiliations__name\">Bell, F G, and Culshaw, M G. 2005. <a href=\"https:\/\/doi.org\/10.1007\/b138363\" target=\"_blank\" rel=\"noopener\">Sinkholes and Subsidence: Karst and Cavernous Rocks in Engineering and Construction<\/a>. (Berlin, Germany: Springer.) DOI: https:\/\/doi.org\/10.1007\/b138363<\/span><\/p>\n\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t<\/div><\/div><\/div><\/div><\/section>\n\n\n\t\t\t\t\t<section   id=\"latest-content-9656-block_5e956f46512a4\" class=\"grid-section  primary-background   \" >\n\t\t\t\t\t\t<div class=\"container\">\n\t\t\t\t\t\t\t\t\t\t\t\t\t<div class=\"row header-of-section\">\n\t\t\t\t\t\t\t\t<div class=\"col-12\">\n\t\t\t\t\t\t\t\t\t<h2>You may also be interested in<\/h2>\n\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t\t\t\t<\/div>\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t<div class=\"row grid-wrap\">\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t<div class=\"col-lg-6 col-12\">\n\t<div class=\"cards cards-orizontal-sm  cards-find-more  cards-bordered\">\n\t\t\t\t<a href=\"https:\/\/www.bgs.ac.uk\/discovering-geology\/\" class=\"media-wrap\">\n\t\t\t<img decoding=\"async\" src=\"https:\/\/www.bgs.ac.uk\/wp-content\/uploads\/2020\/04\/feature_homepage_p815563-150x150.jpg\" class=\"lazy-blur wp-post-image\" alt=\"Ammonite p815563\" data-src=\"https:\/\/www.bgs.ac.uk\/wp-content\/uploads\/2020\/04\/feature_homepage_p815563.jpg\" \/>\t\t\t\t\t<\/a>\n\t\t\t\t<div class=\"info-wrap\">\n\t\t\t<div class=\"info\">\n\t\t\t\t<h4><a href=\"https:\/\/www.bgs.ac.uk\/discovering-geology\/\">Discovering Geology<\/a><\/h4>\n\t\t\t\t\t\t\t\t\t\t\t\t\t<p>Discovering Geology introduces a range of geoscience topics to school-age students and learners of all ages.<\/p>\n\t\t\t\t\t\t\t<\/div>\n\t\t\t<a href=\"https:\/\/www.bgs.ac.uk\/discovering-geology\/\">Show more<\/a>\n\t\t<\/div>\n\t<\/div>\n<\/div>\n<div class=\"col-lg-6 col-12\">\n\t<div class=\"cards cards-orizontal-sm  cards-find-more  cards-bordered\">\n\t\t\t\t<a href=\"https:\/\/www.bgs.ac.uk\/discovering-geology\/earth-hazards\/\" class=\"media-wrap\">\n\t\t\t<img decoding=\"async\" src=\"https:\/\/www.bgs.ac.uk\/wp-content\/uploads\/2020\/05\/feature_hazards_pexels_235807-150x150.jpg\" class=\"lazy-blur wp-post-image\" alt=\"lava flow - Pexels \/ Pixabay\" data-src=\"https:\/\/www.bgs.ac.uk\/wp-content\/uploads\/2020\/05\/feature_hazards_pexels_235807.jpg\" \/>\t\t\t\t\t<\/a>\n\t\t\t\t<div class=\"info-wrap\">\n\t\t\t<div class=\"info\">\n\t\t\t\t<h4><a href=\"https:\/\/www.bgs.ac.uk\/discovering-geology\/earth-hazards\/\">Earth hazards<\/a><\/h4>\n\t\t\t\t\t\t\t\t\t\t\t\t\t<p>The Earth beneath our feet is constantly shifting and moving,  and violently with catastrophic and immediate results. Find out more about earth hazards.<\/p>\n\t\t\t\t\t\t\t<\/div>\n\t\t\t<a href=\"https:\/\/www.bgs.ac.uk\/discovering-geology\/earth-hazards\/\">Show more<\/a>\n\t\t<\/div>\n\t<\/div>\n<\/div>\n\t\t\t\t\t\t\t<\/div>\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t<div class=\"row\">\n\t\t\t\t\t\t\t\t<div class=\"col-12\">\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t\t\t\t<\/div>\n\t\t\t\t\t\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t\t<\/section>\n\t\t\t\t","protected":false},"excerpt":{"rendered":"<p>Sinkholes are hollows that are the result of some kind of collapse of an underlying layer of rock.<\/p>\n","protected":false},"author":2,"featured_media":38208,"parent":3863,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"_acf_changed":false,"_relevanssi_hide_post":"","_relevanssi_hide_content":"","_relevanssi_pin_for_all":"on","_relevanssi_pin_keywords":"karst, sinkhole, shakehole, swallow hole, doline, earth haxards","_relevanssi_unpin_keywords":"","_relevanssi_related_keywords":"","_relevanssi_related_include_ids":"","_relevanssi_related_exclude_ids":"","_relevanssi_related_no_append":"","_relevanssi_related_not_related":"","_relevanssi_related_posts":"8129,21427,6223,30666,17181,17592","_relevanssi_noindex_reason":"","footnotes":""},"tags":[],"acf":[],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v22.3 - https:\/\/yoast.com\/wordpress\/plugins\/seo\/ -->\n<title>Understanding sinkholes and karst - British Geological Survey<\/title>\n<meta name=\"description\" content=\"Sinkholes are often saucer-shaped hollows resulting from some kind of collapse or removal of an underlying layer of rocks.\" \/>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/www.bgs.ac.uk\/discovering-geology\/earth-hazards\/sinkholes\/\" \/>\n<meta property=\"og:locale\" content=\"en_GB\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Understanding sinkholes and karst - British Geological Survey\" \/>\n<meta property=\"og:description\" content=\"Sinkholes are often saucer-shaped hollows resulting from some kind of collapse or removal of an underlying layer of rocks.\" \/>\n<meta property=\"og:url\" content=\"https:\/\/www.bgs.ac.uk\/discovering-geology\/earth-hazards\/sinkholes\/\" \/>\n<meta property=\"og:site_name\" content=\"British Geological Survey\" \/>\n<meta property=\"article:modified_time\" content=\"2021-06-09T13:19:59+00:00\" \/>\n<meta property=\"og:image\" content=\"https:\/\/www.bgs.ac.uk\/wp-content\/uploads\/2020\/06\/Solution_sinkhole_south_wales_website_feature.jpg\" \/>\n\t<meta property=\"og:image:width\" content=\"640\" \/>\n\t<meta property=\"og:image:height\" content=\"430\" \/>\n\t<meta property=\"og:image:type\" content=\"image\/jpeg\" \/>\n<meta name=\"twitter:card\" content=\"summary_large_image\" \/>\n<meta name=\"twitter:label1\" content=\"Estimated reading time\" \/>\n\t<meta name=\"twitter:data1\" content=\"3 minutes\" \/>\n<script type=\"application\/ld+json\" class=\"yoast-schema-graph\">{\"@context\":\"https:\/\/schema.org\",\"@graph\":[{\"@type\":\"WebPage\",\"@id\":\"https:\/\/www.bgs.ac.uk\/discovering-geology\/earth-hazards\/sinkholes\/\",\"url\":\"https:\/\/www.bgs.ac.uk\/discovering-geology\/earth-hazards\/sinkholes\/\",\"name\":\"Understanding sinkholes and karst - British Geological Survey\",\"isPartOf\":{\"@id\":\"https:\/\/www.bgs.ac.uk\/#website\"},\"primaryImageOfPage\":{\"@id\":\"https:\/\/www.bgs.ac.uk\/discovering-geology\/earth-hazards\/sinkholes\/#primaryimage\"},\"image\":{\"@id\":\"https:\/\/www.bgs.ac.uk\/discovering-geology\/earth-hazards\/sinkholes\/#primaryimage\"},\"thumbnailUrl\":\"https:\/\/www.bgs.ac.uk\/wp-content\/uploads\/2020\/06\/Solution_sinkhole_south_wales_website_feature.jpg\",\"datePublished\":\"2020-06-09T06:57:51+00:00\",\"dateModified\":\"2021-06-09T13:19:59+00:00\",\"description\":\"Sinkholes are often saucer-shaped hollows resulting from some kind of collapse or removal of an underlying layer of rocks.\",\"breadcrumb\":{\"@id\":\"https:\/\/www.bgs.ac.uk\/discovering-geology\/earth-hazards\/sinkholes\/#breadcrumb\"},\"inLanguage\":\"en-GB\",\"potentialAction\":[{\"@type\":\"ReadAction\",\"target\":[\"https:\/\/www.bgs.ac.uk\/discovering-geology\/earth-hazards\/sinkholes\/\"]}]},{\"@type\":\"ImageObject\",\"inLanguage\":\"en-GB\",\"@id\":\"https:\/\/www.bgs.ac.uk\/discovering-geology\/earth-hazards\/sinkholes\/#primaryimage\",\"url\":\"https:\/\/www.bgs.ac.uk\/wp-content\/uploads\/2020\/06\/Solution_sinkhole_south_wales_website_feature.jpg\",\"contentUrl\":\"https:\/\/www.bgs.ac.uk\/wp-content\/uploads\/2020\/06\/Solution_sinkhole_south_wales_website_feature.jpg\",\"width\":640,\"height\":430,\"caption\":\"Solution sinkhole on Mynydd Llangynidr, South Wales. 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The stream formed after a high rainfall event. BGS \u00a9UKRI. All rights reserved. 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