{"id":2370,"date":"2019-10-02T19:51:01","date_gmt":"2019-10-02T19:51:01","guid":{"rendered":"https:\/\/www.gsnv.org\/shop\/the-upper-reaches-of-the-sierra-nevada-auriferous-gold-channels-california-and-nevada\/"},"modified":"2020-02-24T18:17:16","modified_gmt":"2020-02-24T18:17:16","slug":"the-upper-reaches-of-the-sierra-nevada-auriferous-gold-channels-california-and-nevada","status":"publish","type":"product","link":"https:\/\/www.gsnv.org\/shop\/the-upper-reaches-of-the-sierra-nevada-auriferous-gold-channels-california-and-nevada\/","title":{"rendered":"The upper reaches of the Sierra Nevada auriferous gold channels, California and Nevada"},"content":{"rendered":"","protected":false},"excerpt":{"rendered":"<p>The world-famous Eocene \u201cAuriferous Gravels\u201d and overlying Oligocene rhyolitic<br \/>\nash-flow tuffs of northern California and adjacent northwestern Nevada lie<br \/>\nunconformably on Mesozoic or Paleozoic basement rocks. These are overlain by volcanic<br \/>\ndeposits of the Miocene ancestral Cascade volcanic arc. The erosion surface<br \/>\nabove the pre-Tertiary rocks represents a considerable hiatus, 40\u201360 Ma, during<br \/>\nwhich time Mesozoic arc volcanics were eroded away. The eroded material was transported<br \/>\nwest across the future Sierra Nevada to the Great Valley sequence of central<br \/>\nand northern California. It is clear that the pre-tuff erosional surface had some relief,<br \/>\nwith a well-developed system of westward-flowing streams in broad paleovalleys in<br \/>\nwestern Nevada and adjacent California. These streams headed in a central Nevada<br \/>\nhighland. Locally, in western Nevada, stream deposits are preserved in the central<br \/>\nparts of these valleys below the rhyolitic ash-flow tuffs. In adjacent eastern California,<br \/>\nthe Oligocene ash-flow tuffs lie on the Auriferous Gravels. In some areas farther<br \/>\nto the west, only Auriferous Gravels are found in the paleovalleys. The source<br \/>\ncalderas of the Oligocene outflow tuffs found in the paleovalleys are apparently all<br \/>\nlocated to the east in western or central Nevada; there are no known sources for these<br \/>\nOligocene ash-flow tuffs in the Sierra Nevada. Recognition that ash-flow tuffs of western<br \/>\nNevada and eastern California can be tied to their Nevada source calderas, and<br \/>\nthat they were deposited mainly in paleovalleys makes it possible to trace the middle<br \/>\nTertiary rivers upstream from where their courses are better known in the western<br \/>\nSierra Nevada.<\/p>\n","protected":false},"featured_media":4751,"comment_status":"closed","ping_status":"closed","template":"","meta":{"pmpro_default_level":""},"product_cat":[154],"product_tag":[],"_links":{"self":[{"href":"https:\/\/www.gsnv.org\/wp-json\/wp\/v2\/product\/2370"}],"collection":[{"href":"https:\/\/www.gsnv.org\/wp-json\/wp\/v2\/product"}],"about":[{"href":"https:\/\/www.gsnv.org\/wp-json\/wp\/v2\/types\/product"}],"replies":[{"embeddable":true,"href":"https:\/\/www.gsnv.org\/wp-json\/wp\/v2\/comments?post=2370"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.gsnv.org\/wp-json\/wp\/v2\/media\/4751"}],"wp:attachment":[{"href":"https:\/\/www.gsnv.org\/wp-json\/wp\/v2\/media?parent=2370"}],"wp:term":[{"taxonomy":"product_cat","embeddable":true,"href":"https:\/\/www.gsnv.org\/wp-json\/wp\/v2\/product_cat?post=2370"},{"taxonomy":"product_tag","embeddable":true,"href":"https:\/\/www.gsnv.org\/wp-json\/wp\/v2\/product_tag?post=2370"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}