{"id":7337,"date":"2025-02-08T16:36:00","date_gmt":"2025-02-08T16:36:00","guid":{"rendered":"https:\/\/rdnhs.org.uk\/blog\/?p=7337"},"modified":"2025-10-27T16:44:17","modified_gmt":"2025-10-27T16:44:17","slug":"curridge-8th-february-2025","status":"publish","type":"post","link":"https:\/\/rdnhs.org.uk\/blog\/curridge-8th-february-2025\/","title":{"rendered":"Curridge – 8th February 2025"},"content":{"rendered":"\n

Lesley Dunlop led a walk to look at the geology of the Curridge area on the cold and misty morning of Saturday 8 February.  Participants gathered at the car park of the Curridge Women\u2019s Institute Hall. Lesley said that we would be looking for some of the pits and hollows which are to be found in the area. The walkers turned left onto Curridge Road, passing a big clump of Butcher\u2019s-broom at the roadside, then turned sharply right along a footpath which headed southwards. Lesley paused to give an introduction to the geology of the area. The bedrock is Chalk, which was laid down about 85 million year ago in warm shallow tropical seas. Then for about 20 million years, the surface of the Chalk was slowly eroded, before the Lambeth beds of sands and clays were laid down in shallow marine, coastal and river environments. Water draining through the iron-rich Lambeth Beds was acid and dissolved the underlying Chalk. Then slowly over time, the Lambeth beds too eroded, leaving the surface of the Chalk pitted by the sink holes which had been created by the Lambeth beds which were no longer there. The big field on the left of the track sloped up to a ridge-line which was capped by Lambeth beds. Looking along the track, a wet area near a small group of trees was the first of the hollows which were being looked for. Several more were seen as the footpath approached Rookery Farm. In small fields on the right were several horses, a Pied Wagtail, a flock of Rooks and a Greenfinch. At the other side of the farm was a business park. Here a hard-standing area for vehicles had recently been extended by quarrying into the slope behind the business park. This had exposed a clear profile of orange Lambeth beds above white Chalk, with Chalk debris above that and other material on top. There are very few places in Berkshire where the junction between the Lambeth Beds and the Chalk can be seen, so this was a significant discovery.<\/p>\n\n\n\n

The walk continued southwards along the footpath. Five Egyptian Geese loomed out of the mist in the middle of the extensive cultivated field on the right. Further on was what was thought to be a wild bird or game bird mix in the field margin, with sunflower heads and also some brassicas. On the left side of the path was a big, deep Chalk pit. The walk continued along the footpath until it came to Long Lane, where another footpath led back north-westwards. On the left side of the footpath was a newly planted Hawthorn hedge which followed the line of big Oak trees which marked the track of the original hedge. The geological map showed a small fault line running ESE-WNW, caused by Africa crashing into Europe. It also showed a band of London Clay on the ridge to the west. Above the London Clay were older river terrace deposits degraded by the freezing and thawing of surface material during the Ice Ages. Water issuing from between the permeable terrace deposits and the impermeable London Clay had lubricated the slump of surface material down the hillside. The big field on the left of the path was cultivated, with a number of small grass-covered conical hills rising up out of the cultivated area. Most of the field was on Chalk, which has the nutrients necessary for growing arable crops. The small conical hills are made up of Sands and Clays of the Lambeth beds. They are nutrient poor and are left uncultivated and covered by grass. These small conical hills were formed by erosion in the last 500,000 years. Many streams drained across the London Clay and eroded the Lambeth group and Chalk layers. Some patches were protected by hard-packed Gravel. The rivers eroded around them, leaving behind these islands of higher ground. Several large reddish-brown sarsen stones were found beside the path. They were formed when the Lambeth Sands were cemented together as the surface water evaporated in tropical conditions that enhanced the solubility of silica. The underlying geology changed from Chalk to the Lambeth beds as the footpath began to climb gently uphill. Tall Burdock plants started to appear beside the path.  Jerry Welsh found a Milk Thistle with variegated leaves, the first West Berkshire record since 1984. The leaves were bright shining green with white veins. Lesley pointed out another hollow on the right of the path. The walkers climbed up into the field on the left to avoid a long puddle which blocked the path. The path led to a track junction. There was a brief diversion straight ahead to a gateway on the north side of Curridge Road, from which two more hollows could be seen. Birds seen here included a small flock of Goldfinches and three Fieldfares, plus Starlings and Chaffinches. Then the route led back to the Women\u2019s Institute Hall car park, where a Treecreeper was feeding on the trunk of an Oak tree.<\/p>\n\n\n\n

Attended by 5 members and by 1 visitor.<\/p>\n\n\n\n

\n
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Chalk – Lambeth beds Boundary – Melinda Lewis<\/figcaption><\/figure>\n\n\n\n
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Chalk – Lambeth beds boundary – Ian Duddle<\/figcaption><\/figure>\n<\/figure>\n","protected":false},"excerpt":{"rendered":"

Lesley Dunlop led a walk to look at the geology of the Curridge area on the cold and misty morning of Saturday 8 February.  Participants…<\/p>\n","protected":false},"author":8,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_customify_content_layout":"","_customify_sidebar":"","_customify_page_header_display":"default","_customify_disable_header":"","_customify_disable_header_top":"","_customify_disable_header_main":"","_customify_disable_header_bottom":"","_customify_disable_page_title":"","_customify_disable_content_vertical_padding":"","_customify_disable_footer_top":"","_customify_disable_footer_main":"","_customify_disable_footer_bottom":"","_customify_breadcrumb_display":"","_customify_header_transparent_display":"","footnotes":""},"categories":[5],"tags":[42,43,40,41],"class_list":["post-7337","post","type-post","status-publish","format-standard","hentry","category-field-trip-reports","tag-chalk","tag-clay","tag-curridge","tag-geology"],"_links":{"self":[{"href":"https:\/\/rdnhs.org.uk\/blog\/wp-json\/wp\/v2\/posts\/7337","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/rdnhs.org.uk\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/rdnhs.org.uk\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/rdnhs.org.uk\/blog\/wp-json\/wp\/v2\/users\/8"}],"replies":[{"embeddable":true,"href":"https:\/\/rdnhs.org.uk\/blog\/wp-json\/wp\/v2\/comments?post=7337"}],"version-history":[{"count":1,"href":"https:\/\/rdnhs.org.uk\/blog\/wp-json\/wp\/v2\/posts\/7337\/revisions"}],"predecessor-version":[{"id":7340,"href":"https:\/\/rdnhs.org.uk\/blog\/wp-json\/wp\/v2\/posts\/7337\/revisions\/7340"}],"wp:attachment":[{"href":"https:\/\/rdnhs.org.uk\/blog\/wp-json\/wp\/v2\/media?parent=7337"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/rdnhs.org.uk\/blog\/wp-json\/wp\/v2\/categories?post=7337"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/rdnhs.org.uk\/blog\/wp-json\/wp\/v2\/tags?post=7337"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}