{"id":1504,"date":"2015-02-13T14:19:45","date_gmt":"2015-02-13T14:19:45","guid":{"rendered":"http:\/\/nantes.apbg.org\/?p=1504"},"modified":"2025-09-23T16:04:21","modified_gmt":"2025-09-23T16:04:21","slug":"voyages-dans-les-alpes-mancelles","status":"publish","type":"post","link":"https:\/\/nantes.apbg.fr\/index.php\/2015\/02\/13\/voyages-dans-les-alpes-mancelles\/","title":{"rendered":"Voyage dans les Alpes mancelles"},"content":{"rendered":"\n<figure class=\"wp-block-image aligncenter size-large is-resized\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"401\" src=\"https:\/\/nantes.apbg.fr\/wp-content\/uploads\/2015\/02\/IMG_0256coupe-1-1024x401.jpg\" alt=\"\" class=\"wp-image-6841\" style=\"width:442px;height:auto\" srcset=\"https:\/\/nantes.apbg.fr\/wp-content\/uploads\/2015\/02\/IMG_0256coupe-1-1024x401.jpg 1024w, https:\/\/nantes.apbg.fr\/wp-content\/uploads\/2015\/02\/IMG_0256coupe-1-300x117.jpg 300w, https:\/\/nantes.apbg.fr\/wp-content\/uploads\/2015\/02\/IMG_0256coupe-1-768x300.jpg 768w, https:\/\/nantes.apbg.fr\/wp-content\/uploads\/2015\/02\/IMG_0256coupe-1-1536x601.jpg 1536w, https:\/\/nantes.apbg.fr\/wp-content\/uploads\/2015\/02\/IMG_0256coupe-1-2048x801.jpg 2048w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\"><\/p>\n\n\n\n<figure class=\"wp-block-image alignright\"><img loading=\"lazy\" decoding=\"async\" width=\"300\" height=\"224\" src=\"https:\/\/nantes.apbg.fr\/wp-content\/uploads\/2025\/09\/IMG_0263bis-300x224.jpg\" alt=\"\" class=\"wp-image-6738\" srcset=\"https:\/\/nantes.apbg.fr\/wp-content\/uploads\/2025\/09\/IMG_0263bis-300x224.jpg 300w, https:\/\/nantes.apbg.fr\/wp-content\/uploads\/2025\/09\/IMG_0263bis-768x574.jpg 768w, https:\/\/nantes.apbg.fr\/wp-content\/uploads\/2025\/09\/IMG_0263bis.jpg 800w\" sizes=\"auto, (max-width: 300px) 100vw, 300px\" \/><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>Le samedi 7 mars 2015,<\/strong> sous la conduite de <strong>Guy Mary,&nbsp;<\/strong>nous avons<strong>&nbsp;<\/strong>voyag\u00e9 \u00e0 travers la caldeira cambrienne d&rsquo;Ass\u00e9-le-Boisne et le synclinal ordovicien de&nbsp; Saint-L\u00e9onard-des-Bois. Orog\u00e9n\u00e8se, volcanisme et g\u00e9omorphologie.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><span style=\"color: #800000;\"><strong>Programme de la journ\u00e9e :<\/strong><\/span><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Le voyage a d\u00e9but\u00e9 par la <strong>d\u00e9couverte de l\u2019anticlinal du pays de Gaultier,<\/strong> dont les bords se d\u00e9marquent dans le paysage par deux lignes de cr\u00eates. (g\u00e9omorphologie)<\/li>\n\n\n\n<li><strong>Des schistes briov\u00e9riens<\/strong>, nous avons\u00a0continu\u00e9 en discordance par des arkoses (avec des conglom\u00e9rats \u00e0 la base) issues de la destruction des granites de la chaine cadomienne, chapeaut\u00e9es \u00e0 un endroit par un massif rhyolitique, faisant partie d\u2019un <strong>complexe volcanique de type caldeira<\/strong>, avec ignimbrite, br\u00e8ches (\u00e0 and\u00e9site) et dacite. Le tout entrecrois\u00e9 de gr\u00e8s de Ste-Suzanne.<\/li>\n\n\n\n<li>Nous\u00a0avons d\u00e9couvert\u00a0ensuite, du parking du cimeti\u00e8re la <strong>discordance entre les schistes briov\u00e9riens et les gr\u00e8s armoricai<\/strong><img loading=\"lazy\" decoding=\"async\" width=\"300\" height=\"224\" class=\"size-medium wp-image-6739 alignright\" src=\"https:\/\/nantes.apbg.fr\/wp-content\/uploads\/2025\/09\/IMG_0280bis-300x224.jpg\" alt=\"\" srcset=\"https:\/\/nantes.apbg.fr\/wp-content\/uploads\/2025\/09\/IMG_0280bis-300x224.jpg 300w, https:\/\/nantes.apbg.fr\/wp-content\/uploads\/2025\/09\/IMG_0280bis-768x574.jpg 768w, https:\/\/nantes.apbg.fr\/wp-content\/uploads\/2025\/09\/IMG_0280bis.jpg 800w\" sizes=\"auto, (max-width: 300px) 100vw, 300px\" \/><strong>ns<\/strong>, qui forment les bords ext\u00e9rieurs du synclinal de St-L\u00e9onard-des-bois. (g\u00e9omorphologie, discordance).Ces gr\u00e8s armoricains contiennent un aquif\u00e8re, dont l\u2019eau est particuli\u00e8rement acide. Mais ils pr\u00e9sentent aussi de jolis \u00ab ripple-marks \u00bb.Puis nous\u00a0avons fait\u00a0la coupe de bord \u00e0 bord du synclinal : gr\u00e8s armoricains \u2013 schistes de Pissot \u2013 gr\u00e9s de May \u2013 schistes de Pissot \u2013 gr\u00e8s armoricains. (orog\u00e9n\u00e8se hercynienne ou varisque, plissement).Au passage, un coup d\u2019\u0153il dans une <strong>carri\u00e8re de gr\u00e8s armoricains<\/strong>, puis rencontre avec le granite cadomien et des <strong>\u00e9boulis p\u00e9riglaciaires<\/strong> de ces gr\u00e8s, \u00e0 des modifications de pentes des schistes (qui ne savent pas se tenir tous seuls !!!) et un petit tour autour des gr\u00e8s de May \u00e0 leur extr\u00e9mit\u00e9 du synclinal. (synclinal tr\u00e8s p\u00e9dagogique \u00e0 \u00ab \u00e9chelle humaine \u00bb).<\/li>\n\n\n\n<li>Ne pas oublier la Sarthe, qui par ses m\u00e9andres, brouille un peu l\u2019orientation dans le site, mais montre une jolie <strong>\u00e9rosion diff\u00e9renci\u00e9e<\/strong> selon la duret\u00e9 des terrains et le r\u00e9seau de faille. (g\u00e9omorphologie, lecture de paysage, \u00e9rosion par l\u2019eau).<\/li>\n<\/ul>\n\n\n\n<p class=\"has-text-align-center wp-block-paragraph\"><span style=\"color: #ff0000;\"><strong>En r\u00e9sum\u00e9 : beau, riche et p\u00e9dagogique !<\/strong><\/span><\/p>\n","protected":false},"excerpt":{"rendered":"<p>Le samedi 7 mars 2015, sous la conduite de Guy Mary,&nbsp;nous avons&nbsp;voyag\u00e9 \u00e0 travers la caldeira cambrienne d&rsquo;Ass\u00e9-le-Boisne et le<\/p>\n","protected":false},"author":1,"featured_media":6843,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"colormag_page_container_layout":"default_layout","colormag_page_sidebar_layout":"default_layout","footnotes":""},"categories":[2],"tags":[],"class_list":["post-1504","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-activites-de-la-regionale"],"_links":{"self":[{"href":"https:\/\/nantes.apbg.fr\/index.php\/wp-json\/wp\/v2\/posts\/1504","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/nantes.apbg.fr\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/nantes.apbg.fr\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/nantes.apbg.fr\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/nantes.apbg.fr\/index.php\/wp-json\/wp\/v2\/comments?post=1504"}],"version-history":[{"count":2,"href":"https:\/\/nantes.apbg.fr\/index.php\/wp-json\/wp\/v2\/posts\/1504\/revisions"}],"predecessor-version":[{"id":6849,"href":"https:\/\/nantes.apbg.fr\/index.php\/wp-json\/wp\/v2\/posts\/1504\/revisions\/6849"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/nantes.apbg.fr\/index.php\/wp-json\/wp\/v2\/media\/6843"}],"wp:attachment":[{"href":"https:\/\/nantes.apbg.fr\/index.php\/wp-json\/wp\/v2\/media?parent=1504"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/nantes.apbg.fr\/index.php\/wp-json\/wp\/v2\/categories?post=1504"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/nantes.apbg.fr\/index.php\/wp-json\/wp\/v2\/tags?post=1504"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}