{"id":56013,"date":"2020-08-20T10:58:02","date_gmt":"2020-08-20T10:58:02","guid":{"rendered":"https:\/\/www.bgs.ac.uk\/?post_type=research_project&#038;p=56013"},"modified":"2020-10-16T12:50:59","modified_gmt":"2020-10-16T12:50:59","slug":"deneholes","status":"publish","type":"research_project","link":"https:\/\/www.bgs.ac.uk\/geology-projects\/sinkholes-research\/deneholes\/","title":{"rendered":"Deneholes"},"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>Deneholes<\/h1>\n\t\t\t\t\t\t\t\t\t<p>BGS Research &mdash; Sinkholes and karst research<\/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\/geology-projects\/sinkholes-research\/deneholes\/\"><span class=\"icon-facebook\"><span class=\"hidden\">Facebook<\/span><\/span><\/a><a target=\"_blank\"  href=\"https:\/\/twitter.com\/intent\/tweet?text=Deneholes&#038;url=https:\/\/www.bgs.ac.uk\/geology-projects\/sinkholes-research\/deneholes\/\"><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\/geology-projects\/sinkholes-research\/deneholes\/\"><span class=\"icon-whatsapp\"><span class=\"hidden\">WhatsApp<\/span><\/span><\/a><a   href=\"mailto:?subject=Deneholes&#038;body=Deneholes%20are%20medieval%20chalk%20extraction%20pits%20comprising%20a%20narrow%20shaft%20with%20a%20number%20of%20chambers%20radiating%20from%20the%20base.%20Their%20historical%20distribution%20is%20not%20well%20known%20and%20they%20can%20cause%20subsidence%20and%20collapses.%20(https:\/\/www.bgs.ac.uk\/geology-projects\/sinkholes-research\/deneholes\/)\"><span class=\"icon-mail\"><span class=\"hidden\">Email<\/span><\/span><\/a><a href=\"#\" data-copy=\"https:\/\/www.bgs.ac.uk\/geology-projects\/sinkholes-research\/deneholes\/\" 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>Deneholes are medieval chalk extraction pits. They characteristically comprise a narrow shaft with a number of chambers radiating from the base and their depth reflects the depth to the underlying chalk bedrock. The shaft width was commonly in the order of 2\u20133&nbsp;m, widening out into galleries at depth.<\/p>\n\n\n\n<p>More recent equivalents (17th to 19th century) are known as chalk-wells and chalkangles (specific to the Berkshire Downs) and are reported to be cruder in construction; both were commonly located close to the field boundaries at the time of extraction.<\/p>\n\n\n<figure  class=\"img-wrap\"><a href=\"https:\/\/www.bgs.ac.uk\/wp-content\/uploads\/2020\/08\/denehole_PJW6247.jpg\" data-toggle=\"lightbox\" data-footer=\"&lt;p&gt;Denehole at Rainham Mark Grammar School, Rainham, Kent, showing the broadening of the cavity beneath the shaft. BGS \u00a9 UKRI.&lt;\/p&gt;\n\" data-gallery=\"gallery_54781\"><img decoding=\"async\" src=\"https:\/\/www.bgs.ac.uk\/wp-content\/uploads\/2020\/08\/denehole_PJW6247-150x150.jpg\" class=\"lazy-blur\" alt=\"Rainham Mark Grammar School: view to show the broadening of the cavity beneath the shaft.\" data-src=\"https:\/\/www.bgs.ac.uk\/wp-content\/uploads\/2020\/08\/denehole_PJW6247.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>Denehole at Rainham Mark Grammar School, Rainham, Kent, showing the broadening of the cavity beneath the shaft. 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\/denehole_PJW6247.jpg\" data-toggle=\"lightbox\" data-footer=\"&lt;p&gt;Denehole at Rainham Mark Grammar School, Rainham, Kent, showing the broadening of the cavity beneath the shaft. BGS \u00a9 UKRI.&lt;\/p&gt;\n\" data-gallery=\"gallery_54781\"><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\">Why were the deneholes dug?<\/h2>\n\n\n\n<p>The chalk was extracted from the deneholes for soil improvement and was usually applied directly to the field. However, sometimes the chalk was processed, which involved burning the chalk in kilns to produce &#8216;quicklime&#8217; (calcium oxide). The addition of water to quicklime formed &#8216;slaked lime&#8217; (calcium hydroxide), which was a white powder that was applied to fields to neutralise acidity or used in the preparation of mortar.<\/p>\n\n\n\n<p>Once they had reached their limits, deneholes were commonly capped. A variety of capping techniques were used, such as upturned trees or brick arching. Records pertaining to the distribution of deneholes are incomplete, sometimes being limited to features marked as shafts or occurrence of circular depressions on historic Ordnance Survey maps. In the field, they are most likely to be visible as shallow depressions, if at all.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Denehole at a Kent school<\/h2>\n\n\n\n<p>The Rainham Mark Grammar School example near Gillingham, Kent, is interesting because the shaft was situated on relatively high ground, possibly reflecting the location of a former field boundary in an area with a relatively thin cover over the chalk.<\/p>\n\n\n\n<p>Bricks in the base of the hole suggest that this feature may once have been capped with a brick arch.<\/p>\n\n\n\t\t\t\t<div  class=\"owl-carousel carousel-primary-color carousel owl-theme thumbs-carousel-js\">\n\t\t\t\t\t<div class=\"item\"><figure  class=\"img-wrap\"><a href=\"https:\/\/www.bgs.ac.uk\/wp-content\/uploads\/2020\/08\/denehole_PJW6280.jpg\" data-toggle=\"lightbox\" data-footer=\"&lt;p&gt;Surface expression of the denehole collapse that occurred on 12 February 2014 at Rainham Mark Grammar School. BGS\u00a0\u00a9 UKRI.&lt;\/p&gt;\n\" data-gallery=\"gallery_45253\"><img decoding=\"async\" src=\"https:\/\/www.bgs.ac.uk\/wp-content\/uploads\/2020\/08\/denehole_PJW6280.jpg\" class=\"attachment-medium size-medium\" alt=\"Rainham Mark Grammar School: surface expression of denehole collapse that occurred on 12 February 2014.\" \/><\/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>Surface expression of the denehole collapse that occurred on 12 February 2014 at Rainham Mark Grammar School. BGS\u00a0\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\/denehole_PJW6280.jpg\" data-toggle=\"lightbox\" data-footer=\"&lt;p&gt;Surface expression of the denehole collapse that occurred on 12 February 2014 at Rainham Mark Grammar School. BGS\u00a0\u00a9 UKRI.&lt;\/p&gt;\n\" data-gallery=\"gallery_45253\"><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><\/div><div class=\"item\"><figure  class=\"img-wrap\"><a href=\"https:\/\/www.bgs.ac.uk\/wp-content\/uploads\/2020\/08\/denehole_PJW6253.jpg\" data-toggle=\"lightbox\" data-footer=\"&lt;p&gt;View into the base of the denehole collapse. BGS\u00a0\u00a9 UKRI.&lt;\/p&gt;\n\" data-gallery=\"gallery_45253\"><img decoding=\"async\" src=\"https:\/\/www.bgs.ac.uk\/wp-content\/uploads\/2020\/08\/denehole_PJW6253.jpg\" class=\"attachment-medium size-medium\" alt=\"Rainham Mark Grammar School: view into the base of the denehole collapse.\" \/><\/a><figcaption class=\"caption sm-line\">\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>View into the base of the denehole collapse. BGS\u00a0\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\/denehole_PJW6253.jpg\" data-toggle=\"lightbox\" data-footer=\"&lt;p&gt;View into the base of the denehole collapse. BGS\u00a0\u00a9 UKRI.&lt;\/p&gt;\n\" data-gallery=\"gallery_45253\"><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><\/div>\t\t\t\t<\/div>\n\t\t\t\t\n\n\n<p>Access courtesy of Mrs D Capelin (School Business Manager) and Mr S Decker (Head Teacher).<\/p>\n<\/div><\/div><\/div><\/section>\n\n\n<section class=\"cta-section  sky-background-d \">\n\t<div class=\"container\">\n\t\t<div class=\"row md-row\">\n\t\t\t<div class=\"col-12\">\n\t\t\t\t<h2>Need more information?<\/h2>\t\t\t\t<div>For more information please contact the Sinkhole team<\/div>\t\t\t\t<div class=\"btn-wrap\"><a href=\"mailto:sinkholes@bgs.ac.uk\"  class=\"button primary-background button btn-icon-arrow-right-white before \">Get in touch<\/a><\/div>\t\t\t<\/div>\n\t\t<\/div>\n\t<\/div>\n<\/section>\n\t\n\n\t\t\t\t\t<section   id=\"latest-content-9858-block_5e7b0d7d9c15e\" 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\/geology-projects\/sinkholes-research\/\" class=\"media-wrap\">\n\t\t\t<img decoding=\"async\" src=\"https:\/\/www.bgs.ac.uk\/wp-content\/uploads\/2020\/08\/P689722-150x150.jpg\" class=\"lazy-blur wp-post-image\" alt=\"Limestone pavement, Cumbria\" data-src=\"https:\/\/www.bgs.ac.uk\/wp-content\/uploads\/2020\/08\/P689722.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\/geology-projects\/sinkholes-research\/\">Sinkholes and karst research<\/a><\/h4>\n\t\t\t\t\t\t\t\t\t\t\t\t\t<p>Our research extends beyond the distribution and processes associated with sinkhole formation to the broader subject of karst.<\/p>\n\t\t\t\t\t\t\t<\/div>\n\t\t\t<a href=\"https:\/\/www.bgs.ac.uk\/geology-projects\/sinkholes-research\/\">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>Deneholes are medieval chalk extraction pits comprising a narrow shaft with a number of chambers radiating from the base. Their historical distribution is not well known and they can cause subsidence and collapses.<\/p>\n","protected":false},"featured_media":56497,"parent":49078,"menu_order":6,"template":"","meta":{"_acf_changed":false,"_relevanssi_hide_post":"","_relevanssi_hide_content":"","_relevanssi_pin_for_all":"","_relevanssi_pin_keywords":"","_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":"16523,17592,7818,17424,16555,15877","_relevanssi_noindex_reason":""},"tags":[],"region":[],"topic":[],"purpose":[],"area":[],"challenge":[],"challenge_topic":[],"acf":[],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v22.3 - https:\/\/yoast.com\/wordpress\/plugins\/seo\/ -->\n<title>Deneholes - British Geological Survey<\/title>\n<meta name=\"description\" content=\"Deneholes are medieval chalk extraction pits; characteristically they comprise a narrow shaft with a number of chambers radiating from the base.\" \/>\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\/geology-projects\/sinkholes-research\/deneholes\/\" \/>\n<meta property=\"og:locale\" content=\"en_GB\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Deneholes - British Geological Survey\" \/>\n<meta property=\"og:description\" content=\"Deneholes are medieval chalk extraction pits; characteristically they comprise a narrow shaft with a number of chambers radiating from the base.\" \/>\n<meta property=\"og:url\" content=\"https:\/\/www.bgs.ac.uk\/geology-projects\/sinkholes-research\/deneholes\/\" \/>\n<meta property=\"og:site_name\" content=\"British Geological Survey\" \/>\n<meta property=\"article:modified_time\" content=\"2020-10-16T12:50:59+00:00\" \/>\n<meta property=\"og:image\" content=\"https:\/\/www.bgs.ac.uk\/wp-content\/uploads\/2020\/08\/denehole_PJW6247_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=\"2 minutes\" \/>\n<script type=\"application\/ld+json\" class=\"yoast-schema-graph\">{\"@context\":\"https:\/\/schema.org\",\"@graph\":[{\"@type\":\"WebPage\",\"@id\":\"https:\/\/www.bgs.ac.uk\/geology-projects\/sinkholes-research\/deneholes\/\",\"url\":\"https:\/\/www.bgs.ac.uk\/geology-projects\/sinkholes-research\/deneholes\/\",\"name\":\"Deneholes - British Geological Survey\",\"isPartOf\":{\"@id\":\"https:\/\/www.bgs.ac.uk\/#website\"},\"primaryImageOfPage\":{\"@id\":\"https:\/\/www.bgs.ac.uk\/geology-projects\/sinkholes-research\/deneholes\/#primaryimage\"},\"image\":{\"@id\":\"https:\/\/www.bgs.ac.uk\/geology-projects\/sinkholes-research\/deneholes\/#primaryimage\"},\"thumbnailUrl\":\"https:\/\/www.bgs.ac.uk\/wp-content\/uploads\/2020\/08\/denehole_PJW6247_feature.jpg\",\"datePublished\":\"2020-08-20T10:58:02+00:00\",\"dateModified\":\"2020-10-16T12:50:59+00:00\",\"description\":\"Deneholes are medieval chalk extraction pits; characteristically they comprise a narrow shaft with a number of chambers radiating from the base.\",\"breadcrumb\":{\"@id\":\"https:\/\/www.bgs.ac.uk\/geology-projects\/sinkholes-research\/deneholes\/#breadcrumb\"},\"inLanguage\":\"en-GB\",\"potentialAction\":[{\"@type\":\"ReadAction\",\"target\":[\"https:\/\/www.bgs.ac.uk\/geology-projects\/sinkholes-research\/deneholes\/\"]}]},{\"@type\":\"ImageObject\",\"inLanguage\":\"en-GB\",\"@id\":\"https:\/\/www.bgs.ac.uk\/geology-projects\/sinkholes-research\/deneholes\/#primaryimage\",\"url\":\"https:\/\/www.bgs.ac.uk\/wp-content\/uploads\/2020\/08\/denehole_PJW6247_feature.jpg\",\"contentUrl\":\"https:\/\/www.bgs.ac.uk\/wp-content\/uploads\/2020\/08\/denehole_PJW6247_feature.jpg\",\"width\":640,\"height\":430,\"caption\":\"Rainham Mark Grammar School: view to show the broadening of the cavity beneath the shaft.\"},{\"@type\":\"BreadcrumbList\",\"@id\":\"https:\/\/www.bgs.ac.uk\/geology-projects\/sinkholes-research\/deneholes\/#breadcrumb\",\"itemListElement\":[{\"@type\":\"ListItem\",\"position\":1,\"name\":\"Home\",\"item\":\"https:\/\/www.bgs.ac.uk\/\"},{\"@type\":\"ListItem\",\"position\":2,\"name\":\"Sinkholes and karst research\",\"item\":\"https:\/\/www.bgs.ac.uk\/geology-projects\/sinkholes-research\/\"},{\"@type\":\"ListItem\",\"position\":3,\"name\":\"Deneholes\"}]},{\"@type\":\"WebSite\",\"@id\":\"https:\/\/www.bgs.ac.uk\/#website\",\"url\":\"https:\/\/www.bgs.ac.uk\/\",\"name\":\"British Geological Survey\",\"description\":\"World-leading geological solutions\",\"publisher\":{\"@id\":\"https:\/\/www.bgs.ac.uk\/#organization\"},\"potentialAction\":[{\"@type\":\"SearchAction\",\"target\":{\"@type\":\"EntryPoint\",\"urlTemplate\":\"https:\/\/www.bgs.ac.uk\/?s={search_term_string}\"},\"query-input\":\"required name=search_term_string\"}],\"inLanguage\":\"en-GB\"},{\"@type\":\"Organization\",\"@id\":\"https:\/\/www.bgs.ac.uk\/#organization\",\"name\":\"British Geological Survey\",\"url\":\"https:\/\/www.bgs.ac.uk\/\",\"logo\":{\"@type\":\"ImageObject\",\"inLanguage\":\"en-GB\",\"@id\":\"https:\/\/www.bgs.ac.uk\/#\/schema\/logo\/image\/\",\"url\":\"https:\/\/www.bgs.ac.uk\/wp-content\/uploads\/2020\/03\/BGS-logo-large.png\",\"contentUrl\":\"https:\/\/www.bgs.ac.uk\/wp-content\/uploads\/2020\/03\/BGS-logo-large.png\",\"width\":250,\"height\":104,\"caption\":\"British Geological Survey\"},\"image\":{\"@id\":\"https:\/\/www.bgs.ac.uk\/#\/schema\/logo\/image\/\"}}]}<\/script>\n<!-- \/ Yoast SEO plugin. -->","yoast_head_json":{"title":"Deneholes - British Geological Survey","description":"Deneholes are medieval chalk extraction pits; characteristically they comprise a narrow shaft with a number of chambers radiating from the base.","robots":{"index":"index","follow":"follow","max-snippet":"max-snippet:-1","max-image-preview":"max-image-preview:large","max-video-preview":"max-video-preview:-1"},"canonical":"https:\/\/www.bgs.ac.uk\/geology-projects\/sinkholes-research\/deneholes\/","og_locale":"en_GB","og_type":"article","og_title":"Deneholes - British Geological Survey","og_description":"Deneholes are medieval chalk extraction pits; characteristically they comprise a narrow shaft with a number of chambers radiating from the base.","og_url":"https:\/\/www.bgs.ac.uk\/geology-projects\/sinkholes-research\/deneholes\/","og_site_name":"British Geological Survey","article_modified_time":"2020-10-16T12:50:59+00:00","og_image":[{"width":640,"height":430,"url":"https:\/\/www.bgs.ac.uk\/wp-content\/uploads\/2020\/08\/denehole_PJW6247_feature.jpg","type":"image\/jpeg"}],"twitter_card":"summary_large_image","twitter_misc":{"Estimated reading time":"2 minutes"},"schema":{"@context":"https:\/\/schema.org","@graph":[{"@type":"WebPage","@id":"https:\/\/www.bgs.ac.uk\/geology-projects\/sinkholes-research\/deneholes\/","url":"https:\/\/www.bgs.ac.uk\/geology-projects\/sinkholes-research\/deneholes\/","name":"Deneholes - British Geological Survey","isPartOf":{"@id":"https:\/\/www.bgs.ac.uk\/#website"},"primaryImageOfPage":{"@id":"https:\/\/www.bgs.ac.uk\/geology-projects\/sinkholes-research\/deneholes\/#primaryimage"},"image":{"@id":"https:\/\/www.bgs.ac.uk\/geology-projects\/sinkholes-research\/deneholes\/#primaryimage"},"thumbnailUrl":"https:\/\/www.bgs.ac.uk\/wp-content\/uploads\/2020\/08\/denehole_PJW6247_feature.jpg","datePublished":"2020-08-20T10:58:02+00:00","dateModified":"2020-10-16T12:50:59+00:00","description":"Deneholes are medieval chalk extraction pits; characteristically they comprise a narrow shaft with a number of chambers radiating from the base.","breadcrumb":{"@id":"https:\/\/www.bgs.ac.uk\/geology-projects\/sinkholes-research\/deneholes\/#breadcrumb"},"inLanguage":"en-GB","potentialAction":[{"@type":"ReadAction","target":["https:\/\/www.bgs.ac.uk\/geology-projects\/sinkholes-research\/deneholes\/"]}]},{"@type":"ImageObject","inLanguage":"en-GB","@id":"https:\/\/www.bgs.ac.uk\/geology-projects\/sinkholes-research\/deneholes\/#primaryimage","url":"https:\/\/www.bgs.ac.uk\/wp-content\/uploads\/2020\/08\/denehole_PJW6247_feature.jpg","contentUrl":"https:\/\/www.bgs.ac.uk\/wp-content\/uploads\/2020\/08\/denehole_PJW6247_feature.jpg","width":640,"height":430,"caption":"Rainham Mark Grammar School: view to show the broadening of the cavity beneath the shaft."},{"@type":"BreadcrumbList","@id":"https:\/\/www.bgs.ac.uk\/geology-projects\/sinkholes-research\/deneholes\/#breadcrumb","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https:\/\/www.bgs.ac.uk\/"},{"@type":"ListItem","position":2,"name":"Sinkholes and karst research","item":"https:\/\/www.bgs.ac.uk\/geology-projects\/sinkholes-research\/"},{"@type":"ListItem","position":3,"name":"Deneholes"}]},{"@type":"WebSite","@id":"https:\/\/www.bgs.ac.uk\/#website","url":"https:\/\/www.bgs.ac.uk\/","name":"British Geological Survey","description":"World-leading geological solutions","publisher":{"@id":"https:\/\/www.bgs.ac.uk\/#organization"},"potentialAction":[{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https:\/\/www.bgs.ac.uk\/?s={search_term_string}"},"query-input":"required name=search_term_string"}],"inLanguage":"en-GB"},{"@type":"Organization","@id":"https:\/\/www.bgs.ac.uk\/#organization","name":"British Geological Survey","url":"https:\/\/www.bgs.ac.uk\/","logo":{"@type":"ImageObject","inLanguage":"en-GB","@id":"https:\/\/www.bgs.ac.uk\/#\/schema\/logo\/image\/","url":"https:\/\/www.bgs.ac.uk\/wp-content\/uploads\/2020\/03\/BGS-logo-large.png","contentUrl":"https:\/\/www.bgs.ac.uk\/wp-content\/uploads\/2020\/03\/BGS-logo-large.png","width":250,"height":104,"caption":"British Geological Survey"},"image":{"@id":"https:\/\/www.bgs.ac.uk\/#\/schema\/logo\/image\/"}}]}},"_links":{"self":[{"href":"https:\/\/www.bgs.ac.uk\/wp-json\/wp\/v2\/research_project\/56013"}],"collection":[{"href":"https:\/\/www.bgs.ac.uk\/wp-json\/wp\/v2\/research_project"}],"about":[{"href":"https:\/\/www.bgs.ac.uk\/wp-json\/wp\/v2\/types\/research_project"}],"version-history":[{"count":22,"href":"https:\/\/www.bgs.ac.uk\/wp-json\/wp\/v2\/research_project\/56013\/revisions"}],"predecessor-version":[{"id":60072,"href":"https:\/\/www.bgs.ac.uk\/wp-json\/wp\/v2\/research_project\/56013\/revisions\/60072"}],"up":[{"embeddable":true,"href":"https:\/\/www.bgs.ac.uk\/wp-json\/wp\/v2\/research_project\/49078"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.bgs.ac.uk\/wp-json\/wp\/v2\/media\/56497"}],"wp:attachment":[{"href":"https:\/\/www.bgs.ac.uk\/wp-json\/wp\/v2\/media?parent=56013"}],"wp:term":[{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.bgs.ac.uk\/wp-json\/wp\/v2\/tags?post=56013"},{"taxonomy":"region","embeddable":true,"href":"https:\/\/www.bgs.ac.uk\/wp-json\/wp\/v2\/region?post=56013"},{"taxonomy":"topic","embeddable":true,"href":"https:\/\/www.bgs.ac.uk\/wp-json\/wp\/v2\/topic?post=56013"},{"taxonomy":"purpose","embeddable":true,"href":"https:\/\/www.bgs.ac.uk\/wp-json\/wp\/v2\/purpose?post=56013"},{"taxonomy":"area","embeddable":true,"href":"https:\/\/www.bgs.ac.uk\/wp-json\/wp\/v2\/area?post=56013"},{"taxonomy":"challenge","embeddable":true,"href":"https:\/\/www.bgs.ac.uk\/wp-json\/wp\/v2\/challenge?post=56013"},{"taxonomy":"challenge_topic","embeddable":true,"href":"https:\/\/www.bgs.ac.uk\/wp-json\/wp\/v2\/challenge_topic?post=56013"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}