Hikers: Gather at the Quail Creek Reservoir Park (Hiway 9, or State St. to hiway 318, north one mile to Park  on right side), at 9 am Wed. 2 Feb, for a hike at the base of the dam, climbing the hill to the east. We will be in the middle of an anticline, crossing some gypsum beds (wallboard raw material), ascending to the middle of the Triassic, where petrified wood is found in the Chinle (if lucky).Arrive before 9am and look at the geological description of the stratigraphy on the notice board, memorizing the names of the triassic formations, and the order in which they occur from the base (oldest). Park at the overlook in the park, where we will see the lake and dam. WE will hike about two miles, but bring lunch and sturdy shoes.
 I have gotten input from paricipants that lay-observations are avavilable- we will incorporate these, to confirm in the field:
 

A couple of things that may be of interest to you.

1. Brown bag lecture at the BLM office. Its free. Call or visit office
for
free tickets.

    Subject: Little Known Geothermal Resources of Southern Utah
    Speaker: Bob Blackett
    Date: 11 February 2005
    Time: 1200-1300
    Location: 345 E. Riverside Dr., St. George
    Phone: 435-688-3246

2. Hollow formation near Sullivan Knoll.

Phyllis Lawton is in charge of the Hurricane Pioneer Heritage Park. Her
husband, Gregory, has a story to tell concerning the hollow formation
at the
back of the Sullivan Knoll cinder cone which he discovered when
preparing
the hole for the water tank.

Phone: 435-635-4696, Cell: 435-680-2621

I talked to you about the hollow on you hike last Tuesday.  We enjoyed
the
hike and look forward to the hike next week Wednesday.

Jerry Schwantz & Jacqueline Dubois
 

 
 
 On 25th Jan, we climbed the older volcanic dome (near the Hurricane City park), S27 T41N R13W, to get the view looking north, east, and west of the local Geology.
 Four trends were apparent:
1. The Hurricane Fault generally trends N-S, in this area, and is evidently still uplifting on its East side. A 3.6 Ricter earthquake occured on 19 Dec, epi-centered near Cedar City, near this fault; there are hot springs at the crossing of the Virgin R. at La Verkin (recently relieved by drilling nearby), the Kaibab cliffs east of Toquerville are shear (as with recent activity), and erosion is scanty in many places- indicating youthfulness of the fault, I would guess that the uplift is about 1 mm/year (1/25th inch, or so);
2. The Pine Valley Mts. trend NE-SW, as do Virgin Anticline and local hills on the edges- this is apparently from an ancient weakness brought on by the Laramide compressional forces (70 my. years ago and later), leaving the local area weak in this direction; However, the fact that the general trend is N-S in northern AZ and S.Utah, indicates that there is a local anomaly in this area- something on the kiloscopic scale (kilometer and more). We will look at the local geology on three scales:
a. Megascopic: regional, such as the Colorado Plateau;
b. Kiloscopic- 10 km or so;
c Macroscopic- meter scale, which is pertinient for rocks you can caress, or measure with well logging processes;
c. Microscopic- samples seen by the hand lens, or microscope.
3. The regional fracture system, which may be measured with a compass, as being NW-SE, is apparent, and it occurs over most of the Western US, except for the Puget Sound NW, and some of the Basin and Range. Locally the system may veer to the N-S, as it does at the Kaibab Uplift.
 This evidently is due to weaknesses developed whenever the Laramide Conmpressional forces caused weaknesses in the whole Colorado Plateau. These have been retained, due to breakage of brittle rock during that time, and re-express themselves whenever the mantle introduces new stresses. This can be seen at the V. Overlook, as a fracture and fault running NW-SE and a fault contact of volcanic rocks on two sides of the Mesozoic sandstones. Since this cuts the volcanic rocks as well as the Mesozoic, the fault is younger than the few million year age extrusives (I emphasize that the fault runs NW-SE, which is definitely different than the Hurricane N-S system.
4.A new feature, which we will try to understand, are the E-W fractures creating canyons through the Kaibab Uplift. These may just be orthogonal (perpendiocular) to the main N-S fault system, and we will try to solve this riddle this year.
5. Both uneroded limonite-colored bombs, about football-size, and vesicular basalts were found representing different episodes of the extrusion- the bombs being the younger of the two.
Most bombs were already split by ice or impacts, indicating that this extrusion is on the order of 100,000 years age (as compared to Sullivan's Knoll- which appears top be of the 10,000 year category.
Harold L. Overton

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