English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Tools annual

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Presents the access of premium content as premium feature

Premium Content

Global: Zendy Plus annual

Global: Zendy Free Plan

The igneous rocks of the San Francisco Mountain volcanic center are so variable lithologically and so complexly related structurally and stratigraphically that they are described below in detail in order to make the geologic map more useful. San Francisco Mountain is a composite volcano that was constructed largely during the Quaternary from several silicic lava domes and at least two stratovolcano cones consisting of interlayered lava flows and pyroclastic deposits of andesitic to rhyolitic composition. The volcano rests on a platform of nearly horizontal Paleozoic, and possibly Triassic, strata plus Quaternary or Tertiary basalt lava flows. Dissection of San Francisco Mountain has provided an exceptional view of the core of the volcano, where over 900 m of volcanic rocks are exposed in the Inner Basin and Interior Valley. Because of the exposures, a large number of rock units have been recognized and mapped, and their stratigraphic relationships are interpreted with a relatively high degree of confidence. In spite of the deep dissection, nearly 900 m of igneous rocks, presumably including some of the oldest lavas, still remain buried beneath the Inner Basin. The breach in the northeast flank of the mountain originated from collapse late in the development of the volcano. Paleozoic sedimentary rocks that crop out on and near Elden Mountain and Little Elden Mountain were tilted and faulted during emplacement of the dacite intrusions and older dacite of Elden Mountain. Structural relationships on the east side of Elden Mountain indicate that the strata were initially pushed up to steep dips and later subsided by rotation normal to strike and displacement along normal faults. Anomalous thicknesses of two or three of the Paleozoic formations imply duplication of beds by faults that must strike nearly parallel to the beds, but such faults have not been located or documented.

Geologic map of San Francisco Mountain, Elden Mountain, and Dry Lake Hills, Coconino County, Arizona