Open Thread - Black Friday Equals Mad Max
6 hours ago
|The way to work|
Looking eastward at the top of the ridgeline on Mount Elden, standing on the Sunset Trail on Quarternary dacite. From this vantage point, several features of the eastern sedimentary block can be observed. The Heart Trail begins at this point and descends nearly the entire uplifted block, terminating two miles later, approximately 1500 vertical feet below, at the base of the mountain.
Dacite spires above the Martin formation contact looking southeast. Kluth believes that these spires, which appear sporadically at a common elevation across this face of the mountain, were formed at the point of contact between the dacitic material and the sedimentary layers which are found immediately below them.
Sedimentary layers (foreground) below the dacite spires (background) looking westward. Two distinctly different rock colorations can be seen at this point. Kluth identifies the initial sedimentary unit in this vicinity as the Jerome member of the Devonian Martin formation. He ascribes to it an olive green to brown color, becoming bleached white where it contacts igneous material. The material on the left fits this description. He identifies the next unit as the Mississippian Redwall. In this vicinity he describes it as greyish in color, fitting the material on the right side of this photograph.
Standing in the light colored Devonian-Mississippian Martin-Redwall material looking eastward the contact between these units and the subsequent orange-red Pennsylvanian Supai group below is easy to identify. Kluth notes that the Supai group is identifiable only on this flank of Mount Elden. Due to fracturing it forms talus slopes instead of cliffs.
According to both Kluth and Johnson, this feature should be located within the Pennsylvanian Supai group. Here, looking southwest, the bedding planes can be seen to be steeply inclined. Kluth notes that the uplifted Supai material on the eastern block of Mount Elden dip between 50-70 degrees in a southeasterly direction; this feature would seem to comply.
Looking westward, immediately below the red sandstone of the Pennsylvanian Supai group, there are several small outcroppings of a lithologically different rock. Kluth and Johnson both indicate the presence of early Permian Hermit shale in this vicinity though Kluth indicates that the shales in this region have not been accurately mapped. Johnson indicates a large deposit of Hermit shale placing it between the Supai group and the Schnebly Hill formation.
A point of contact that appears to correspond with Johnson as the darker red Schnebly Hill formation (left) and buff-colored Coconino-Toroweap (right). Kluth identifies this vicinity as the boundary between the Supai and undifferentiated Coconino-Toroweap without mentioning the Schnebly Hill formation. Kluth also identifies the nearby sandstone knobs as the edge of the upturned eastern block.
Looking southwest, below the previous contact the sandstone material is now uniformly buff-colored. This loose fine-grained material seems to fit with Kluth’s description. Likewise, Kluth notes that within the Coco-weap exposures the material forms broad flat parks. Here, in its last mile, as the trail begins to traverse less steeply inclined terrain, a mixing of materials, chiefly sandstones, limestones and volcanics, also becomes evident.
Looking southeast at an outcropping of red sandstone immediately adjacent to the trail that appears to correspond to Johnson as an isolated emplacement of the Schnebly Hill formation within the alluvial surface material at the base of the mountain.
Two miles and 1500 vertical feet later, looking west, at the terminus of the Heart Trail. Here the geologic material is identified by Kluth and Johnson as a mixture of surficial deposits. The Heart Trail does not appear to cross any sizable, identifiable outcroppings of early Permian Kaibab limestone; however, the presence of such material would appear to be evident in the vicinity, particularly as a major component of the sandy park and small white knob immediately north and east of this position.