Slickensides in the Hurricane fault zone (scarp)

These Slickensides are more extensive on hiway 9 cliffs, east of the shoulder, on the north part of hte Graben
This is the most massive Slickensides found- you should study it to use as an
Example for Future Finds; notice the Linear Striations and Grooves of hardened surface (probably silicates) precipitated from warm water flowing along the previous Subsurface Fault Face (original composition was Limestone, CaCO3)

The South view of Graben shows where it started (Water tank sits on Graben Downthrown Block)

Westward, the Upthrown Block shows a 15 Degree departure from Vertical (West Edge of Graben wall moved northward, as well as Vertically)

Eastward, the Upthrown Block Has Almost-Vertical Striations, indicating that the Plunge to north has little influence on the orientation
Graben Slickensides show Direction of Crustal Movement

Shown above and below are photos of “Skid Marks” or slickensides in the walls and Scarps above the town of Hurricane, in the Hurricane Fault, Hf to the east. These are the result of the rasping of one block of the Crust, as it moved relative to another block which is more stationary. These are primarily the work of normal faulting, which is unknown as to origin, but they give details of the movement in one local area. They may yield understanding of the larger underlying event which has Hf as a final result. The movement which produced the slickensides is very deliberate and slow, so that the final product is slick and contains regular lines and a glassy portrait of the direction and type of movement.
First, notice that the surface of the slickensides is so well-polished that it shines in the sunlight. The two blocks which slid relative to each other are of similar composition, and therefore of similar hardness. This causes the honed surface to appear extremely fine-grained.
Secondly, the surface is discolored in the millimeter or so thickness which is preserved. This is caused by the heat which is generated by the friction of rubbing, which changes the solubility of compounds in the water which has found the fractured and faulted space. The drop-out of iron compounds and other solutes in the water makes the surface harder than it was originally- initially calcite or limestone, which is soft (3 on Moh’s hardness scale).
Thirdly, small grains of hard material entrained in the moving block remain un-dissolved long enough to leave a line or trough, which indicates the direction of the movement. For a graben, this movement should be vertical, since this is a normal fault, happening under extension. However, the deviation from vertical is striking and regular for the west wall of the graben, which is the upthrown block (the downthrown block cannot be seen, because it has fallen into the earth).

Preliminary Conclusions:
1. The west wall of the graben has slickensides with striations dipping down into the earth- Down-to-the-South. Since the graben plunges down to the north, part of this 15 degree angle is due to rotation of the graben as it plunges down to the north (look at the larger photo of the whole graben, where the incipience or start of the graben is shown to be less than a kilometer to the south).

A Closeup of east wall of the Graben shows Striations resulting from "Drag" of Downthrown Block hard pebble inclusions- which leave parallel grooves.


2. The east wall of the graben (again the upthrown block) has a few degrees dip down to the north. This is not significant, and may be approximated as vertical, but the importance is that it shows that the plunge of the graben to the north is not a significant contribution to the deviation from vertical.

The Detailed Closeup of Striations (East Wall) show the angle of deviation as less than 5 Degrees, indicating that Plunge of Graben is not the Primary Factor causing the movement away from Verticality in the West Graben Wall
3. Since the graben west wall is the one showing deviation from vertical of the drop of the downthrown block, this indicates that we are looking a phenomenon which is occurring closer to Hf proper. Although the entire graben is part of Hf, and there is transfer of stress to form the graben, the entire result can be interpreted as part of the total movement of Hf. In this case, generalizing, the rim of the graben is moving north with the time of fall of the graben relative to the downthrown block. This would be a right-lateral fault, with movement laterally caused by something other than gravity (a weight of rock simply falling- due to gravitational attraction- as the earth is pulled apart). The lateral movement would be due to a compressive force, such as rotation of the Colorado Plateau, CP.
4. This right-lateral faulting is representative only of the graben where it is found but could be an indication of further investigation to determine whether it is representative of CP as a whole (at least on the western side, near the Pine Valley Mountains and local volcanism which bear on it- all Post-Laramide features).

The Massiveness of the Slicks shows that they were the Result of a continuous Sliding, and the Regularity indicates a slow movement which was heated by the Friction- allowing Water to Rearrange its Chemical Contents over significant time (NOT lurching)



A Rare image shows that there was occasionally a Disruption in the Graben Sliding- an interference

Hiking in Arroyos East of Laverkin, UT quarry

Large Slumping Angles (faulting Dip- down to West)occur East of Quarry



Laverkin Quarry and slumping near Hf (S11, 13 T41S R13W)

A Google space photo is shown, to indicate the geographic and topographic changes near Hiway 9- ascending the cliffs, toward the town of Virgin, Utah. Orient your view by looking at the switchbacks to the east of the town and to the Black ridge to the north. Hf heads north between this mesa and the extension of it NE of Toquerville (the Pleistocene basalts have been sliced by Hf- which has several splays near Laverkin and Toquerville). Use the Freeway I-15 as a guide for focusing your gaze onto something familiar. Ash Creek is the N-S waterway to the west, and Laverkin Creek is east of that- flowing through the valley to the east of the Black Ridge. Hf has bifurcated, creating the weaknesses which allow the two creeks to parallel each other.
It is difficult to ascertain the quarry and faulting-slumping on this map, but it is just to the north of the obvious switchback on hiway 9. The quarry lies just east of the crossing of hiway 17 bridge over Laverkin Creek- being a light area, which is the result of digging and slumping. No hint is given of obvious fracturing, but Hf is easily followed by looking for the change of elevation along the scarp.
The N-S orientation of the fault can be readily seen, and it will be emphasized in photos, which show the fractures and their orthogonals (fractures which are at right angles to the dominant fractures seen in the outcropping rocks) along the path. The main interest is to answer the following questions:
1. Why does the fault create so many splays in the area of the quarry (helping to create the deposit, which has allowed more slumping as it is removed; the ancient river found these weaknesses and eroded more easily there, dumping its load of gravel in the ancient meanders or river bows)?
2. Is there movement laterally along the fault? Slickensides, near a graben on the rim above Laverkin, indicate that there is right lateral movement going toward Toquerville (a counterclockwise movement of the Colorado Plateau, CP).
3. Is there a continuity to the opening of a major fracture underlying Wet Sandy Creek NW of Toquerville- producing the large spring in Ash Creek there- proceeding along Hf to the south, and then to the quarry location and on up the Hf scarp towards the Virgin fissures to the SE? This would make a¯\ _ trace on a map, where the hyphens orient NW-SE and the diagonal underlies Hf.
4. In the field, we will look at the bedding angles displayed between the various faults or slumps, to see if there is rotation of the blocks as they slumped to the west and then rotated with a reverse movement later? This would happen if Hf has interfered, through time, with the slumping or faulting process.
5. Upon zooming in on the north side of the Virgin River (Search Google Earth), a faint NW-SE trace can be seen heading toward Laverkin quarry?, but the pixel density does not allow an inspection of this anomaly. This must be followed in the field.
6. There are various orientations of the major fractures shown on the map, both from the drastic turns of the river and with the mesas and scarps shown. Are these orientations consistent with a major fracture system?

Comments made after Re-Hiking the Laverkin quarry Arroyo:
a. A possible answer to 1, is that there is a transfer of movement (and of the stresses causing it) westward at Hf in this location. This has probably caused not only the multiple faulting splays, but has weakened the fractured zone to allow the ancient Laverkin Creek to enter the fractures.
b. There is movement laterally along Hf, but it has several possible reasons: CP may be rotating, the graben which abuts the slickensides has rotated downward (starting south just uphill from the slickensides), and there is slumping laterally- not only west from the slickensides, but also north. The entire lateral movement may just be a local feature, not part of the CP proper.
c. For 3, undoubtedly the large flowing spring at Toquerville indicates continuity for a fluid path, and the water flow is likely from the Pine Valley Mountains, but there are other large elevation gradients present, e.g. from the Zion NP region.
d. For 4, there is definitely a change of the bedding slope as seen in the Quarry Arroyo. The type of deposit is the only evidence showing reverse dip angle- large dip indicates there should be boulders in the deposit (there aren’t any in the lower strata), whereas slight dip angle in the overlying deposit indicate that there shouldn’t be boulders (they are present in the walls above the larger dip sediments).

e. The zoom-in of the area just north of the Virgin does show a color change on a line running NW-SE. This disappears before reaching the Hiway 9 switchback, but then this is the most distorted surface area (close to Hf, as it creates an up-to-the west bending of the crust);


and,
f. The answer to 6 is not yet found.


Google Earth Map shows the gross landforms without regard to Geological Terms

Laverkin Quarry and slumping near Hf (S11, 13 T41S R13W)

Exercise in Dating (relatively) Hurricane's Cones and Craters

This View shows the eroded West Hurricane Crater. WHC, Rim, with Pine Valley Mountains in the distance

This Cone has been Quarried for red ash, which is excellent for Road Covering
View from W Hurricane Crater (S27 T41S R13W)
Included are several photos, which were taken from the rim of the W Hurricane Crater. This cone and crater are located about midway between the crater at the Stout Park, SPC, and that at Sullivan’s Knoll, (SK)- all within 2 km of each other. Although they are not a line, WHC lies between the two others within the Huricane city limits. Both of these other craters are shown in the photos, and you should try to answer the following question as you view them:
Q. Considering the three craters as a set of extrusions from a similar source, what is the relative age of WHC (oldest, youngest or in-between)?
You will see the following clues, as you take the hike to the summit of the rim:
1. This crater, although better preserved than the one to the east, is the lowest in elevation of all three;
2. The other cones have basalt exposed at their base, while this cone is predominantly red ash and scoria, or lapilli;
3. This cone has an erosional path just off its east side, which is lower than the basalt levees exiting from the SPC;
4. This crater rim retains the rough shape of a crater, with erosional breaks, but then it is lower in elevation and has been subject to a smaller gradient for precipitation-causing erosion; and,
5. WHC contains the best deposit of red ash for Road Metal (makes excellent shoulders and coating for icy roads).
Facts and Terms:
The initial basaltic eruptions occurred about 100-200 kilo-years before the present time (kybp) for all three of these craters, although the cones and explosive craters are much younger and are more siliceous- not basalt. Surface evidence can only be applied to the final emission for each case, since the rock at the base has been eroded and mostly covered. Basalt came first, evidently from large fractures which had insufficient time to incorporate wall rock containing larger amounts of silica (sand and shale) because of the faster velocity of the magma.
Crater is the interior depression of a cone, much smaller than a caldera.
Extrusions are eruptions which have occurred on the earth’s surface as flows, blasts, solid movements, or gaseous displays.
Intrusions are magma movements which never reached the earth’s surface, but which may have a similar composition to extrusions which did- e.g. granite, diorite, or gabbro (proceeding towards the less common outcrops, after erosion of the cover). Granite is equivalent to extrusive rhyolite, diorite to andesite, and gabbro to basalt in composition.
Lapilli are sand size particles, from 2-64 millimeters (about 1/13 inch to 2.5 inches), up to cobble size.
Scoria is deposition from the original blast, as from a solid and gaseous suspension in the sky (cinders, clinker, and ash may be other names).
Types of Vulcanism:
a. Cone: a small protrusion from the main volcano or magma source, which is cone-shaped before erosion, e.g. Sullivan’s Knoll or Veyo;
b. Shield, or volcano with a slight slope (resembling a warrior’s shield), such as Mauna Loy in Hawaii- this is predominately composed of basalt; and,
c. Strata or composite: A large cone with large slope and indications of multi- eruptions- alternately flows, blasts, and puddling of lavas (doming), e.g. Fuji.
d. Vulcanism around the Pacific Rim is mainly Andesitic (from the Andes Mountains name), and is explosive- high silica content- while volcanoes from the interior of continents and isolated islands are mainly basaltic and slow-flowing (high iron content from the Mantle). The reason for the explosive vulcanism around the Rim is due to the high silica content as the various plates dive into the Crust and absorb continental sedimentary rocks (with their large amounts of sandstones and shales). This feature along with the larger fraction of water in the crust yields explosive magma before the subduction reaches the Mantle and its mainly basaltic composition.
e. When basalt is encountered, it indicates mantle or deep Crustal flows, whereas explosive vulcanism denotes recycling of Crustal sediments or Metasediments.




Laverkin Hogback, formed by cooling of subsurface after vulcanism ceased is to NE




West of WHC lies a tongue of Basalt, originating from SK
2nd Hike around the rim of the SW Crater

A complete circuit was made around the rim of the West Crater, WHC, to determine the age relative to the other cones occurring within the Hurricane city limits. The rim is eroded in only one location- the southern edge, where erosion has opened a drainage way. Next to this drainage there is a 4th dome, which has a dike and possible sill protuding from the older WHC, and it is composed of rock from magma which has flowed rather than blasted- not the same as the iron-colored extruded blasts (it has a lighter grey color, and is layered, but containms some olivine). This rock is younger than WHC, since it has sliced through the red ash cone, and there are vertical and horiontal rocks exposed- protruding from the red ash. The dome has no crater but does have loose red ash, and it is higher than WHC in elevation; it appears to have flowed laterally and verically, without volatility.
This dome is closer in distance to SK, not quite aligned with it and SPC.

West of WHC lies a tongue of Basalt, originating from SK

It appears that the dome has risen after the basalt flows of SK and SPC (having a lighter color and composition than either of them), but of age later WHC. Its lack of excessive erosion indicates that the following eruptions occurred (oldest time first):
1. Basalt flowed near WHC location, and then proceeded to flow further west, finally damming the Virgin River near hiway 9 bridge (at least 3 flows).
2. A dome of more siliceous (low density basalt formed, with dikes, west of WHC (this dike has somewhat bedded red ash sloping down toward it, so must have pierced the redbeds;
3. Blasts occurred first at SPC, then at WHC (this is a weak conclusion), and lastly at SK;
4. Erosion affected SK the most, followed by SPC, and finally WHC, because of the lesser erosional gradient (elevation) there.


A Fourth Dome occurs on the rim of WHC- but probably older than it



West of WHC lies a tongue of Basalt, originating from SK

2nd Hike around the rim of the W Crater

A complete circuit was made around the rim of the SW Crater, WHC, to determine the age relative to the other cones occurring within the Hurricane city limits. The rim is eroded in only one location- the southern edge, where erosion has opened a drainage way. Next to this drainage there is a 4th dome, which is obviously older than SWHC, and it is composed of rock from magma which has flowed rather than blasted- not basalt, but dacite or rhyolite (it has a light color, and is layered). This rock is older than SWHC, since it has been eroded to make way for the red ash cone, and there is a dike of similar material which is on the edge- protruding from the red ash. The dome has no crater or red ash, and it is higher than WHC in elevation; it appears to have flowed laterally, without volatility.
This dome is closer in distance to SK, not quite aligned with it and SPC.

West of WHC lies a tongue of Basalt, originating from SK


It appears that the dome has risen after the basalt flows of SK and SPC (having a more silicic composition than either of them), but prior to WHC. Its lack of excessive erosion indicates that the following of eruptions occurred (oldest time first):
1. Basalt flowed near WHC location, and then proceeded to flow further west, finally damming the Virgin River near hiway 9 bridge (at least 3 flows).
2. A dome of Dacite formed, with dikes, west of WHC;
3. Blasts occurred first at SPC, then at SWHC, and lastly at SK;
4. Erosion affected SK the most, followed by SPC, and finally WHC, because of the lesser erosional gradient (elevation) there.


A Fourth Dome occurs on the rim of WHC- but probably older than it

The "Big Picture", as seen in Zion Park (Model)

This Photo was taken askew deliberately, to allow you to look obliquely


Zion NP Model Frame orients N-S, with Virgin tracing the fractures of 2+ mybp


Notice that there are two sets of strains (Fractures), not quite orthogonal to each other in this National Park Model of the Colorado Plateau- Zion NP, but Coal Pits Creek to the west of this view shows that in the last million years a new orientation has superseded these.

Detail of Structural Rearrangements to N of Crater

A Young Hogback has been Created by Surface Sediments rotating into the void left by Magma evacuation (greatest along the Hurricane Fault)

Ancient and Current Earth Movements near Hurricane and its namesake Fault
Refer to accompanying photos, to see the movements revealed in the rocks outcropping near the lands bordering the Hurricane Fault, Hf: S 26, 27, 34 & 35, T41S, R13W, Utah.
Hikes and Field Trips during the years 2004-07, by our local Earth Science group ( www.PorOgle.blogspot.com ), have shown that the Earth’s Crust is moving continuously in the region near Hf, in several ways:
1. The Colorado Plateau, CP, is uplifting- relative to the Basin and Range, B&R, to the west- along Hf;
2. Additional subsidence along the same fault occurs on the west side, due to past evacuation of magma through several vents. Although the vulcanism is not active now, the shrinkage of the cooling subsurface rock causes the overlying surface rock to sink into the contracting space and form Hogbacks running north to south, N-S (more so near the fault);

Look Carefully, and you will see changes in dip on the west side of the Hogback, as distance from nearby vents increases

3. CP, in addition to uplifting, is rotating along Hf in a right lateral manner, as shown by slickensides on the east side of Hf;
4. There is undulation of the rock segments along Hf, where some crust moves more than its neighboring outcrops. This creates lenses of contrasting-movement rock, as well as grabens along Hf;
5. There are large fracture systems which intersect Hf, creating multi-faulting segments in the outcrops. These appear to trace NW-SE, contrasting with the N-S trending Hf. At the intersection there is instability, such as in the Laverkin quarry. One such trace moves SE from the Pine Valley Mountains, PVM, along the Wet Sandy Creek towards Toquerville (possibly feeding the Ash Creek Spring there), and then traces along Hf until reaching the quarry- where the trace moves SE toward the large fissures above the Virgin River, near the diversion dam west of the town of Virgin;
6. The Crust occasionally shakes from unknown causes, with earthquakes, such as happened in 1992; and,
7. There is abnormal expansion due to geothermal activity, such as that at Pah Tempe and near the Veyo volcanic cone.
8. Large scale fracture systems, which by definition have little movement along them, exhibit shear in NW-SE linears and probably maintain openings in the sheared rock- so that fluids may move slowly along the linears.
All of the above movements or tendencies manifest themselves in the rocks as shown in accompanying photos. The trick is to verify the movements by looking at what appears to be static earth, but is in actuality motion at a rate which the eye cannot directly determine. Rather, the motion must be found from clues such as open fissures, inability of erosion to keep up with the uplift or downdrop, unsteady abnormal temperatures, spring water anomalies, strange rock movements, and landslides.


Dip Irregularities are noticeable along the West edge of the Hogback (looking north)


Basalt Flows entered the ancient Virgin River, as well as through Faults and Fractures

Grand Geological View to N, from Hurricane Crater

Looking North along Hurricane Fault

Looking N across Virgin River presents Turmoil to West and CP undisturbed Beds to East (across Hurricane Fault)

NW Hurricane has a Crater with a low Rim remaining (beside Gould's Wash)

Young Meanders in an actively-uplifting Area- Hurricane, UT

The large View of the Sky Mountain Golf Rim and its nearby Meander, above the Virgin River

Closeup View of Meander and Conglomerates

How can the Virgin River have a “youthful” Meander, in an area (Zion Highlands and Hurricane Fault) which has been uplifting for millions of years?

Meanders are created in streams which are old (for the sections of rivers where they occur). A meander requires that there be almost no stream gradient, that is, the velocity of the water is low enough to prevent active downcutting of the river bed- rather, the stream works sluggishly and laterally as in the Mississippi River, seen in lower Louisiana (almost at sea level elevation).

The Hogback northwest of the Virgin shows the severity of the slopes due to compression (uplift and Buckling)

An area which is uplifting will develop a high energy stream- with a rapid current. This will not allow a meander to develop. However, accompanying photos show not only a meander below Sky Mountain Golf course in Hurricane, but also flat and level conglomerates or sandstones which would be typical for a place where the sediments were dumped (the current was reduced to near zero, and its sediment load was placed in the river bed). The Virgin River is known to become violent sometime during each year, either when the snow melt washes down, or during the summer monsoon when violent storms develop. How then, did the large meander and its flat and level conglomerates form (in this area of ancient beds which are rapidly changing in elevation, with obvious drastic slopes and cliffs)?


Cooling Cracks create Hexagonal Columns, as the lava shrinks (Similar to Mud Cracks forming multi-sided blocks- but due to shrinkage by drying rather than cooling)
The answer is found by looking at the vulcanism which is also presented in the photos. Melted Basalt flows similarly to river water- running into the low elevation locations and displacing water (in the city limits of Hurricane, there are at least 3 young volcanic craters with age less than 200,000 years). This creates a damming of the previous river and develops a lake in its place. A lake has no noticeable current, and any sediment flowing down from nearby rivers would drop to the bottom- creating a sedimentary bed. A conglomerate is one type of deposit, indicating that indeed the streams feeding the lake had high energy (enough to bring in large boulders), but that the lake had a sluggish velocity. This low energy stream would create a meander, and the surrounding cliffs would be subject to wave action of the lake and to softening due to ice and annual weather- allowing the river loop or oxbow to enlarge sideways. This is a Meander and it would be restricted by the surrounding pre-existing cliffs and volcanic deposits. Incidentally, a meander is named after the original feature in Turkey seen by me, in the Menderes (a family name, made famous by a recent Turkish Premier) River- over which the ancient town of Ephesus presides.

Conglomerates (Cobbles and Boulders) are flat and almost level on both sides of the Meander

Eventually the water in the lake raises enough to broach the volcanic dam downstream, after which the increasing current would not only downcut the previous conglomerates but straighten the river. The first noticeable remains of this action is one of several canyons cutting the beds younger than (on top of) the conglomerates, where the river is low enough in elevation, to allow the youngest sediments to remain for us to see.
Look through the series of photos, to determine whether you can see the sequence of events, occurring over the last 100,000 years:
1. Sudden damming of the Virgin River by a basalt flow;

Volcanic Basalts flows are heavy and dark, filling the low spots where the Virgin resided- creating a dam for a Meander

2. Creation of a conglomerate bed, which is almost flat and level, at an almost constant elevation over the length of the meander;

View of Plc conglomerates on south side of Meander

View of the Plc Conglomerates on north side of Meander

3. Breaching of the volcanic dam, allowing the river to downcut previous beds and basalts;


4. Formation of small canyons in the beds in the center of the meander, as the rapidly-flowing water eroded the lake bed and surroundings;

5. Creation of side canyons, still continuing today, an example of which is Gould’s Wash flowing from the Hurricane Fault on the east side of town; and
6. Downcutting of the whole area by a fast-moving Virgin River, creating deep canyons and steep banks in the area of the volcanic basalts.


Before the vulcanism, there were flat and almost level sandstones of about 200,000 years age- which are seen on both sides of the Virgin River



Gould's Wash (A Canyon in this location) has eroded rapidly into the Virgin- showing how fast the fractured basalt shears



When first breached, the river level was higher- cutting small washes into the youngest sediments