Thursday, April 26, 2007

Glenn's Early Art



INUKSHUK (Glenn Wassom, Sept 04)

The wilds of the North my feet have trod,
On distant lands known but to God;
How great the hubris to explore,
Where no man’s feet have gone before.

How astonishing then, it was to see
A marking cairn that startled me;
It appeared from nowhere, a stone mirage-
One carefully built of bricolage.

That stack of rocks had a human look
Which I later learned was an Inukshuk;
It clearly signified a human code
To knowing ones who used this road.

Danger ahead? A good hunting spot?
A gathering place that time forgot?
What mysteries these stones conceal-
I’d love to learn what they’d reveal.

But one thing I learned from that effigy,
I was not the first this route to see.
It intrigues us all, to know the past-
I thought to be first, but was really last.

Wednesday, April 25, 2007

Respects to the Premier River of the West

Song of the Colorado River

Relentless, forceful, surging- goes the prelude
When I listen to the sounds
Of the Premier Western river, as it hastens ever seaward
On its annual cleansing rounds.

It has a duty, never ending
As it drives on to the sea,
To disperse the excess baggage
Which Living Things have caused to be.

How it sings about its’ seasons
As it goes about its’ chores-
First a whisper, then a babble,
Then a splashing along its’ shores.

Soon it’s surging, then it’s roaring-
As it widens in its' prime-
Giving life to myriad creatures,
And a setting for a rhyme.

How it fits into the psyche
Of the artist on its’ bank-
Annual Rhythm, cleansing Ritual,
Life Renewal, Canyons dank.

But its’ Song is more possessing
For the Spirit of mankind
As it stimulates the Vital-
At the center of our mind.

No! The very Core of our existence
Which is very rarely struck,
Is soon singing with the River,
As our heartstrings get a pluck.


Finally, there’s a crashing- yea Crescendo,
As the cataracts soon give way
To the Bedrock of the lake beds, where
Serenity, as Life, manifests its final say.

Harold L. Overton

Geologic Maps and Section for I-15 and Pintura


Sample Earth Science Hike, PVM Laccolith, Utah


Oak Grove Earth Science Hike along the Wilderness Area Boundary (S8, 9 T40S R14W): Apr 10/07, PVM
To access this border of the Pine Valley Mountains, SE side, exit I-15 on the north side of the freeway at the town of Leeds, Utah, then proceed northward on the Silver Reef road for two miles to a fork leading northward toward the Oak Grove Campground (graveled after crossing the creek). Just short of 8 miles from I-15, take a right fork to the trailhead to Columbine Spring, skirting the Wilderness area (this is a 100 meter dead end road, ending at the trailhead). Hiking north, there is a Tee at which good views to the east, of sedimentary outcrops, may be accessed. Follow this trail to the lowest point where you can then access the contact of igneous and sedimentary rocks by walking uphill cross-country in a dry wash.
This area has intrusive rocks, Tip, in contact with older Tertiary and Mesozoic outcrops; expect the following scenario:
1. The Miocene 21mybp intrusion (Pine Valley Mountains) rose to a kilometer or less depth (below ground surface) in Tertiary times, and then it moved outwardly and formed the shape of a mushroom on the SE side of the melt. I expect this since this is the situation with many salt domes (which are also hot plastic-flow rocks). At about this depth, it is easier to lift the overburden than to vertically fracture it, and the melt moves laterally- forming a sill or dikes. This problem has been solved by engineering, and the depth of the change in direction depends upon Poisson’s ratio and for the sediments to have essentially no strength for shear (the Tertiary Claron Tc or underlying Cretaceous most likely fits this requirement). The lateral hoop stress is about twice the normal stress (S: lateral=μ x Vertical, overburden stress, ~ .5 x depth x 1.2 psi/foot x 2 for a hoop, whereas Sv is ~ 1 psi/ft) for an intrusion pushing either outward or upward), and the rising melt cannot easily vertically fracture the overlying rocks- rather the movement proceeds laterally.
Note: Tc is divided into at least two vertical sections by geologic mappers, and the lower is the pink or red found on this hike; it has a total thickness no greater than 2300 feet (about 700 meters) near Cedar City, Utah. If the melt reached the upper Tc, it would have been no more than 1000 feet below ground surface in Miocene time.
2. The melt (quartz monzonite) was an intrusion- never reaching the surface of the ground. Nevertheless, there it is exposed in the Pine Valley Mountains (PVM). Since large crystals and grains are portrayed in the igneous rocks (requiring a long slow cooling period), they definitely were covered while cooling- otherwise the rock would be glassy or aphanitic, without large crystals. The fact that the ground mass in the rock has fine crystals surrounding larger grains indicates that the large grains formed at depth with the slow cooling; the large grains would have formed before the hot mass reached a shallow depth where more rapid cooling of finer crystals occurred. To become exposed, the overlying Tertiary and Cretaceous rocks must have been eroded later, exposing some kilometer thickness of igneous rock (as seen now- from about 7,000 at the sedimentary contact to 10,000 feet at the highest mountain). This has happened in the 21 my time since emplacement. Since the soft sediments eroded rapidly, compared to the igneous rock, there was exposed to the air the PVM and its surrounding sills and dikes.
3. The surface geological map shows some granite-like igneous rocks (monzonite) with Tc on three sides in the lands to the SE of PVM, near Anderson Junction at I-15. These rocks are all too low in the section (compared to their original appearance higher up the PVM); consequently they must have moved since their emplacement. This is shown by the appearance of older rocks, such as Jn, Navajo sandstone, in a fairly normal circumstance nearby. For the case where Tc borders the intrusive rocks at an abnormally low elevation, one of the following must have occurred:
a. A dike or sill occurred below the top of Tc (at less than one km depth, in Miocene times), and after erosion of Tcu (upper) some 3000 or more feet, the whole mass moved down the mountain by creep. Keep in mind that under the overhang of igneous sills there would have occurred a normal section of sedimentary rock which was by-passed by the upwardly-buoyed laccolith nearby (to the NW). When Engineer M. King Hubbard proposed this mechanism 50 years ago for large-scale thrusting, it was derided by geologists as “solving geological problems, such as thrusting and generation of overpressure, by lubrication”. Nevertheless, after the dynamics of earth movements were investigated using physics, it was found that this is the likely mechanism for the movement of large blocks of rock associated with Geopressure- particularly over rock with a large component of fine grains (clay or shale). The overlying block of earth slides over a temporary cushion of over-pressured shale, allowing easy movement; or
b. The block of igneous rock on the SE side of PVM, surrounded by Tc was higher in elevation originally, but has since dropped with normal faulting. I think this likelihood is low, since the nearby columns of igneous rock as far away as five miles have performed similarly. Most igneous masses on the SE side of PVM do not have bordering Tc, so they could either have been original dikes off the main laccolith or could have detached separately. This detachment mechanism has been investigated extensively in AZ, and the underlying rock is usually highly metamorphosed. I find none of this in this location, and the likelihood is again low; or
c. The dikes are still in their original position, at least for those not having bordering Tc or Cretaceous rocks; they would not have moved (for these outcrops), but could have occurred because of the previously investigated Weak Zone on the SE side of PVM. It is interesting that there is no obvious Tip on the west side of PVM, and that extrusion occurs on the north side. Further, the cursory look at the west side seems to have sediments down-dipping against PVM (the opposite of what you would expect for a compressive intrusion); hence the melt incorporated the silicates to yield the characteristic quartz monzonite and did not shove north or westward. Extrusion (basalts and other flows) on the north side indicates that extension occurred there.

Oak Grove, PVM hike, cont'd


d. The fact that the obvious anomalies occur on the SE side yields additional suspicion that PVM has shoved toward the SE- either causing the weak zone or exploiting it. The present tilt of Pk peak near the Toquerville spring at an unusual angle (almost 45 degrees- greater than the Virgin anticline nearby) further indicates that PVM intrusion has compressed the SE region and not the region NW of PVM. In other words, the rise of PVM was toward the SE- pulling away from the northwest, and shoving toward the SE. This allowed extrusion to occur on the NW side where extension was occurring, simultaneously with compression of sediments on the SE side.
Observations made in the field, bearing on the structural history of PVM:
There are many outcrops of Mesozoic rocks in the Oak Grove area which generally indicate the following:
a. Sedimentary beds abut the intrusion without showing lateral distortion. Some may be nearly one hundred meters wide in a single outcrop;
b. The beds, however, are tilted generally down toward the intrusion while running parallel to it (SW-NE). This may be interpreted in at least 2 ways:
I. The beds in large blocks have slid sufficiently and at such a large sliding angle (nearby intrusive rocks rise upwardly at about 60-70 degrees), that they rotated into the monzonite as the underlying ground surface angle to the SE lessened; or
II. The sedimentary column has not necessarily slid from its original position, but has shrunk by thermal contraction near the border of PVM, as the melt contracted with cooling. This would make the beds closer to the laccolith appear to drop with cooling, while the more distant beds remained at a constant datum. One would then ask “Why would the individual beds not have shrunk by the same amount as they originally expanded by laccolith heating?” One answer can be: Sedimentary rock may expand upon heating in an almost permanent manner, due to heat strengthening and replacement of the original calcitic for silicate cement, but the overall porosity decrease must be greater with the heating and cooling cycle (for there to be an overall reduction of stratigraphic column thickness- as is postulated). Hot fluids dissolve more silica than cold, and the acidity of the hot water has changed. The reduction in porosity must be greater than permanent fractional matrix (cementation or solid) increase, for the final stratigraphic column to drop after cooling. The strengthened beds might then become somewhat contracted while the entire stratigraphic column dropped, while the solid intrusion was cooling and shrinking (the monzonite would have no porosity in its original unfractured condition, and some of the original quartz in the sediments would have dissolved in the melt). An ancillary question would be: “What happened to the beds far away from the melt, where they never expanded in the first place?” This cannot be answered without measuring the distant bed thickness, and the appropriate outcrops are not available for measurement. They would have been uninfluenced by both heating and cooling (to remain high relative to the beds closer to PVM), for dipping to occur near the PVM. This entire explanation depends upon a geochemical rearrangement, for shortening of the stratigraphic column next to the melt to occur.
Reviewing, as the melt initially moved through the deepest part of Tc (by incorporation of the sedimentary rock) it forced the water contents of the rocks outwardly. This steam or hot water moved laterally through the surrounding porous rocks- reducing the porosity of the sediments by dissolution- and dumping the dissolved rock further away in the cooler rocks. Later, this increased distant mass remained relatively at its original elevation while the rock closer to the laccolith shrunk with cooling.
III. The original dip of the sedimentary column may be part of the present configuration, but the Mesozoic on the western side of the PVM indicates a similar dipping into the mountain, so that it is likely that we are looking at a general result of the intrusive process. The best conclusion from all of this is that sedimentary beds in contact with PVM indicate that there was no compression of the beds upward (of the North and West contacts) and that melting of sediments caused the incorporation of additional quartz into the melt (hence quartz monzonite), robbing the stratigraphic column of mass.
My inclination is to give option I the greatest likelihood, with the chance that we can tell the amount of sliding by the amount of dip toward the Laccolith. That is, the greater the dip angle toward the monzonite, the greater the distance that the sedimentary rock (or its associated dike-like rock) has slid down the mountain (because of the lesser slope of the ground surface further from the palisades). For sedimentary beds with dip angle essentially at zero, this would indicate no sliding- that is, the rock would have remained at its pre-laccolith orientation. This would be case for an original overhang of sill of the granite-like rock.
A comparison of the Tip outcrops standing alone on the SE side of PVM may yield some additional information about their incipience (ones having no surface contact with older beds of Claron Tc or sedimentary rocks). There are several of these dike-like igneous outcrops on the SE side of PVM, and a look at the grain and fracture patterns in these may be instructive.
The hiking group climbed cross-country to the contact of the Claron (pink fine-grained siltstone), collected samples of it and made photos of the contact zone. See these in the attachments.
While the Cretaceous sandstones below Tc are generally monotonous and flat and level (near the trail), they yield an observation about the possibility of detachment or sliding of the monzonite:

Tertiary Beds (Tc, Claron upper) abutting PVM

Anomaly to SE, enlargement



The sedimentary layers uphill from a dike-like deposit of monzonite (near Columbine spring and trail) on the kilometer scale in extent, are flat and level, undistorted- indicating that the dike could not have slid over them.
At the outcrop of Tc higher in the section, there is a major wash, which has many parallel fractures trending 150 degrees from north, in the adjacent monzonite laccolith. Further, above the fractures there is a saddle with scree- indicating a normal fault or active fractures. It appears that Tc has dropped down to the NE across the wash- all of these features exist on a NW-SE trend pointing to a saddle in the mesa near the town of Apple Valley. On this same trend there is a volcanic plug protruding from the skyline south of the hiway to Kanab (UT 59). All of this reinforces my projection that there is a major weakness extending from PVM toward the SE, through the hiway 9 switchbacks east of Laverkin toward the major fissures near the Virgin River.
This PVM and surrounding area should be statistically evaluated to confirm the following features:
1. Older (than Miocene) sedimentary beds abutting the laccolith have a dip into the igneous rock which depends upon the amount of sliding of the sedimentary column. Rock dropping and rotating will have the largest dip for the largest drop;
2. Tc, Claron, beds with no dip indicate no sliding, and nearby downhill igneous rock would be the location of an overhanging sill which has dropped into place (without distortion of the originally deeper sedimentary beds);
3. Sliding and dropping of Tc and associated monzonite occurs mainly on the SE side of the laccolith;
4. Extrusive rocks and undistorted sedimentary rocks are the normal circumstance for the NW side of PVM;
5. NW PVM is characterized by extension regionally, while SE of the mountains there is local compression (such as with the Pk peak north of Toquerville); and
6. Large-scale NW-SE fracturing and possibly lateral faulting has occurred since Miocene time in the region, affecting the topography all the way to the Virgin River.
This exercise using field analysis shows what can be done in the field using simple measurements and logic. There are 30 of these Earth Science hikes reported in the geohikes link shown on the right side of the Blog. Comments are invited from readers, to fortify or reject the various conclusions.
Attached are some photos, which show the general topography of the region near the Oak Grove Park, with its associated sedimentary and igneous rocks:

Pine Valley Mountain View to SE


Oak Grove Earth Science Hike along the Wilderness Area Boundary (S8, 9 T40S R14W): Apr 10/07, PVM
To access this border of the Pine Valley Mountains, SE side, exit I-15 on the north side of the freeway at the town of Leeds, Utah, then proceed northward on the Silver Reef road for two miles to a fork leading northward toward the Oak Grove Campground (graveled after crossing the creek). Just short of 8 miles from I-15, take a right fork to the trailhead to Columbine Spring, skirting the Wilderness area (this is a 100 meter dead end road, ending at the trailhead). Hiking north, there is a Tee at which good views to the east, of sedimentary outcrops, may be accessed. Follow this trail to the lowest point where you can then access the contact of igneous and sedimentary rocks by walking uphill cross-country in a dry wash.
This area has intrusive rocks, Tip, in contact with older Tertiary and Mesozoic outcrops; expect the following scenario:
1. The Miocene 21mybp intrusion (Pine Valley Mountains) rose to a kilometer or less depth (below ground surface) in Tertiary times, and then it moved outwardly and formed the shape of a mushroom on the SE side of the melt. I expect this since this is the situation with many salt domes (which are also hot plastic-flow rocks). At about this depth, it is easier to lift the overburden than to vertically fracture it, and the melt moves laterally- forming a sill or dikes. This problem has been solved by engineering, and the depth of the change in direction depends upon Poisson’s ratio and for the sediments to have essentially no strength for shear (the Tertiary Claron Tc or underlying Cretaceous most likely fits this requirement). The lateral hoop stress is about twice the normal stress (S: lateral=μ x Vertical, overburden stress, ~ .5 x depth x 1.2 psi/foot x 2 for a hoop, whereas Sv is ~ 1 psi/ft) for an intrusion pushing either outward or upward), and the rising melt cannot more easily vertically fracture the overlying rocks- rather the movement proceeds laterally.
Note: Tc is divided into at least two vertical sections by geologic mappers, and the lower is the pink or red found on this hike; it has a total thickness no greater than 2300 feet (about 700 meters) near Cedar City, Utah. If the melt reached the upper Tc, it would have been no more than 1000 feet below ground surface in Miocene time.
2. The melt (quartz monzonite) was an intrusion- never reaching the surface of the ground. Nevertheless, there it is exposed in the Pine Valley Mountains (PVM). Since large crystals and grains are portrayed in the igneous rocks (requiring a long slow cooling period), they definitely were covered while cooling- otherwise the rock would be glassy or aphanitic, without large crystals. The fact that the ground mass in the rock has fine crystals surrounding larger grains indicates that the large grains formed at depth with the slow cooling; the large grains would have formed before the hot mass reached a shallow depth where more rapid cooling of finer crystals occurred. To become exposed, the overlying Tertiary and Cretaceous rocks must have been eroded later, exposing some kilometer thickness of igneous rock (as seen now- from about 7,000 at the sedimentary contact to 10,000 feet at the highest mountain). This has happened in the 21 my time since emplacement. Since the soft sediments eroded rapidly, compared to the igneous rock, there was exposed to the air the PVM and its surrounding sills and dikes.
3. The surface geological map shows some granite-like igneous rocks (monzonite) with Tc on three sides in the lands to the SE of PVM, near Anderson Junction at I-15. These rocks are all too low in the section (compared to their original appearance higher up the PVM); consequently they must have moved since their emplacement. This is shown by the appearance of older rocks, such as Jn, Navajo sandstone, in a fairly normal circumstance nearby. For the case where Tc borders the intrusive rocks at an abnormally low elevation, one of the following must have occurred:
a. A dike or sill occurred below the top of Tc (at less than one km depth, in Miocene times), and after erosion of Tcu (upper) some 3000 or more feet, the whole mass moved down the mountain by creep. Keep in mind that under the overhang of igneous sills there would have occurred a normal section of sedimentary rock which was by-passed by the upwardly-buoyed laccolith nearby (to the NW). When Engineer M. King Hubbard proposed this mechanism 50 years ago for large-scale thrusting, it was derided by geologists as “solving geological problems, such as thrusting and generation of overpressure, by lubrication”. Nevertheless, after the dynamics of earth movements were investigated using physics, it was found that this is the likely mechanism for the movement of large blocks of rock associated with Geopressure- particularly over rock with a large component of fine grains (clay or shale). The overlying block of earth slides over a temporary cushion of over-pressured shale, allowing easy movement; or
b. The block of igneous rock on the SE side of PVM, surrounded by Tc was higher in elevation originally, but has since dropped with normal faulting. I think this likelihood is low, since the nearby columns of igneous rock as far away as five miles have performed similarly. Most igneous masses on the SE side of PVM do not have bordering Tc, so they could either have been original dikes off the main laccolith or could have detached separately. This detachment mechanism has been investigated extensively in AZ, and the underlying rock is usually highly metamorphosed. I find none of this in this location, and the likelihood is again low; or
c. The dikes are still in their original position, at least for those not having bordering Tc or Cretaceous rocks; they would not have moved (for these outcrops), but could have occurred because of the previously investigated Weak Zone on the SE side of PVM. It is interesting that there is no obvious Tip on the west side of PVM, and that extrusion occurs on the north side. Further, the cursory look at the west side seems to have sediments down-dipping against PVM (the opposite of what you would expect for a compressive intrusion); hence the melt incorporated the silicates to yield the characteristic quartz monzonite and did not shove north or westward. Extrusion (basalts and other flows) on the north side indicates that extension occurred there.


d. The fact that the obvious anomalies occur on the SE side yields additional suspicion that PVM has shoved toward the SE- either causing the weak zone or exploiting it. The present tilt of Pk peak near the Toquerville spring at an unusual angle (almost 45 degrees- greater than the Virgin anticline nearby) further indicates that PVM intrusion has compressed the SE region and not the region NW of PVM. In other words, the rise of PVM was toward the SE- pulling away from the northwest, and shoving toward the SE. This allowed extrusion to occur on the NW side where extension was occurring, simultaneously with compression of sediments on the SE side.
Observations made in the field, bearing on the structural history of PVM:
There are many outcrops of Mesozoic rocks in the Oak Grove area which generally indicate the following:
a. Sedimentary beds abut the intrusion without showing lateral distortion. Some may be nearly one hundred meters wide in a single outcrop;
b. The beds, however, are tilted generally down toward the intrusion while running parallel to it (SW-NE). This may be interpreted in at least 2 ways:
I. The beds in large blocks have slid sufficiently and at such a large sliding angle (nearby intrusive rocks rise upwardly at about 60-70 degrees), that they rotated into the monzonite as the underlying ground surface angle to the SE lessened; or
II. The sedimentary column has not necessarily slid from its original position, but has shrunk by thermal contraction near the border of PVM, as the melt contracted with cooling. This would make the beds closer to the laccolith appear to drop with cooling, while the more distant beds remained at a constant datum. One would then ask “Why would the individual beds not have shrunk by the same amount as they originally expanded by laccolith heating?” One answer can be: Sedimentary rock may expand upon heating in an almost permanent manner, due to heat strengthening and replacement of the original calcitic for silicate cement, but the overall porosity decrease must be greater with the heating and cooling cycle (for there to be an overall reduction of stratigraphic column thickness- as is postulated). Hot fluids dissolve more silica than cold, and the acidity of the hot water has changed. The reduction in porosity must be greater than permanent fractional matrix (cementation or solid) increase, for the final stratigraphic column to drop after cooling. The strengthened beds might then become somewhat contracted while the entire stratigraphic column dropped, while the solid intrusion was cooling and shrinking (the monzonite would have no porosity in its original unfractured condition, and some of the original quartz in the sediments would have dissolved in the melt). An ancillary question would be: “What happened to the beds far away from the melt, where they never expanded in the first place?” This cannot be answered without measuring the distant bed thickness, and the appropriate outcrops are not available for measurement. They would have been uninfluenced by both heating and cooling (to remain high relative to the beds closer to PVM), for dipping to occur near the PVM. This entire explanation depends upon a geochemical rearrangement, for shortening of the stratigraphic column next to the melt to occur.
Reviewing, as the melt initially moved through the deepest part of Tc (by incorporation of the sedimentary rock) it forced the water contents of the rocks outwardly. This steam or hot water moved laterally through the surrounding porous rocks- reducing the porosity of the sediments by dissolution- and dumping the dissolved rock further away in the cooler rocks. Later, this increased distant mass remained relatively at its original elevation while the rock closer to the laccolith shrunk with cooling.
III. The original dip of the sedimentary column may be part of the present configuration, but the Mesozoic on the western side of the PVM indicates a similar dipping into the mountain, so that it is likely that we are looking at a general result of the intrusive process. The best conclusion from all of this is that sedimentary beds in contact with PVM indicate that there was no compression of the beds upward (of the North and West contacts) and that melting of sediments caused the incorporation of additional quartz into the melt (hence quartz monzonite), robbing the stratigraphic column of mass.
My inclination is to give option I the greatest likelihood, with the chance that we can tell the amount of sliding by the amount of dip toward the Laccolith. That is, the greater the dip angle toward the monzonite, the greater the distance that the sedimentary rock (or its associated dike-like rock) has slid down the mountain (because of the lesser slope of the ground surface further from the palisades). For sedimentary beds with dip angle essentially at zero, this would indicate no sliding- that is, the rock would have remained at its pre-laccolith orientation. This would be case for an original overhang of sill of the granite-like rock.
A comparison of the Tip outcrops standing alone on the SE side of PVM may yield some additional information about their incipience (ones having no surface contact with older beds of Claron Tc or sedimentary rocks). There are several of these dike-like igneous outcrops on the SE side of PVM, and a look at the grain and fracture patterns in these may be instructive.
The hiking group climbed cross-country to the contact of the Claron (pink fine-grained siltstone), collected samples of it and made photos of the contact zone. See these in the attachments.
While the Cretaceous sandstones below Tc are generally monotonous and flat and level (near the trail), they yield an observation about the possibility of detachment or sliding of the monzonite:


The sedimentary layers uphill from a dike-like deposit of monzonite (near Columbine spring and trail) on the kilometer scale in extent, are flat and level, undistorted- indicating that the dike could not have slid over them.
At the outcrop of Tc higher in the section, there is a major wash, which has many parallel fractures trending 150 degrees from north, in the adjacent monzonite laccolith. Further, above the fractures there is a saddle with scree- indicating a normal fault or active fractures. It appears that Tc has dropped down to the NE across the wash- all of these features exist on a NW-SE trend pointing to a saddle in the mesa near the town of Apple Valley. On this same trend there is a volcanic plug protruding from the skyline south of the hiway to Kanab (UT 59). All of this reinforces my projection that there is a major weakness extending from PVM toward the SE, through the hiway 9 switchbacks east of Laverkin toward the major fissures near the Virgin River.
This PVM and surrounding area should be statistically evaluated to confirm the following features:
1. Older (than Miocene) sedimentary beds abutting the laccolith have a dip into the igneous rock which depends upon the amount of sliding of the sedimentary column. Rock dropping and rotating will have the largest dip for the largest drop;
2. Tc, Claron, beds with no dip indicate no sliding, and nearby downhill igneous rock would be the location of an overhanging sill which has dropped into place (without distortion of the originally deeper sedimentary beds);
3. Sliding and dropping of Tc and associated monzonite occurs mainly on the SE side of the laccolith;
4. Extrusive rocks and undistorted sedimentary rocks are the normal circumstance for the NW side of PVM;
5. NW PVM is characterized by extension regionally, while SE of the mountains there is local compression (such as with the Pk peak north of Toquerville); and
6. Large-scale NW-SE fracturing and possibly lateral faulting has occurred since Miocene time in the region, affecting the topography all the way to the Virgin River.
This exercise using field analysis shows what can be done in the field using simple measurements and logic. There are 30 of these Earth Science hikes reported in the geohikes link shown on the right side of the Blog. Comments are invited from readers, to fortify or reject the various conclusions.
Attached are some photos, which show the general topography of the region near the Oak Grove Park, with its associated sedimentary and igneous rocks:

Tuesday, April 24, 2007

Inside Passage Elderhostel




Passage to Skagway

It was a dreary and foggy day, when the two erstwhile Elderhostelers eked out an earnest edge into the eponymous echoes of hostile Elders.
H&H strode manfully (and semi-womanly) during the summer of 2006 toward their destiny- hopefully not their Doom- on the good ship Malaspina. The entire name of the Alaskan State Tub was Mal-asp-in-a-vessel. And it was aptly christened, since a onerous snake was necessary to Roto-Root the commode of the statuesque stateroom in student’s steerage with its first usage.
The geological half of the Dynamic Duo observed immediately that Bellingham, where the Alaskan Marine Highway (AMH) originated its voyage, was founded upon Lummi Sandstone (eponymously named after the town where Lummi natives had previously subsisted). This Tertiary stone was to give way to mostly metamorphic rocks along the Inside Passage toward Skagway at the edge of the Lynn Canal- a 50 mile linear feature oriented almost north-south along part of the route. This, of course, is in accordance with rules of equatorial contraction caused by shrinkage of the Earth’s ellipsoidal bulge, as the daily spin rate of the earth decreases with Time (less than one milli-second of time of rotation per year, which would yield a shortening of about 17 minutes per million years of rotation of the earth-which would shrink the low latitude diameter of the Globe).
The Elderhostel ergonomically-expressed egregious earthlings were led by a resident of Adolphus, Alaska (thank salvation for a celebration of alliteration) - one John Scheerens. The group consisted of 38 professionals- mostly teachers and medical workers- representing states as distant as Florida and Maine. Little did they realize that they were embarking through a slice of the biological community where they were to see Death and Destruction on a massive scale- heretofore un-witnessed by themselves.
After sunny frivolity through British Columbia, the ship crept eerily through fog banks, mizzle, and drist, where low-hanging clouds seeped into the very marrow of their perspicacious personalities. It was only at ol’ Russian Sitka where they would be restored by ol’ Sol.
Although this gregarious group was physically able to walk lustily through the towns encountered along the route, they were somewhat inhibited by the fact that the good ship would only stop for a short time in each port. The Elderhostelers would have to be content to gaze expectantly through the portholes and windows at the villages. They were rewarded at the larger towns of Sitka, Skagway, Juneau and Ketchikan, with tours of at least an hour each, where roads and buses were provided for touring. The most invigorating tour occurred at Sitka, where a hike was taken through the National Park. Here there could be seen the migration of the salmon and some geology in the cliffs. Fortunately, the AMH had provided time for lectures and films to be shown onboard. The two Tongass Forest Service Naturalists- Andrea Mogil and Lori- each had specialties which they indulged, and the cultures of the Tlingits, Haida, and Tsimshians were accentuated.
Lori was very gregarious, and started several ventures, soliciting Trivia and Tongue twisters to stimulate writing. Below is my contribution:

During the 19th century, Haida natives made incursions as far south as Whidbey Island in Washington state, and once in retaliation for the execution of a chief, sought a notable in the town of Coupeville, Island County, Washington, for execution. Finding no medical doctor (which they thought to be on the order of a shaman), they took the mail carrier- a rising political star. He was beheaded, after which the Haida retreated to SE Alaska.

Haida Hid Hacked Heads Here; Had Hapless Heathen Harangued Helplessly?

The voyage through the Inside Passage is a working trip, with no frivolities. It is the main method for accessing SE Alaska, except by air, and it affords an inexpensive way of scanning the geography of this out-of-the-mainstream part of North America. College students, oil workers, military people, and transients use the ships of the Alaskan state system to access the area. One miner told me this story:
“The easily panned gold has been taken, but one can dig deeper in the old river channels (now covered), for by-passed placers.” He selects an area where gold has been panned, and digs a few feet below the worked-out claim, or alternatively, nearby in a now dry abandoned channel. Since this was previously the path of the stream which later produced shallower waterways, buried gold may be occasionally found in fossil stream beds which earlier had been carrying gold from the same area- as is now contained in the active streams. He was full of enthusiasm for his 60 year age, and his bedraggled appearance belied his intention to “Strike it Rich”.
Although the allowed meal expenditure was less than $180, this figure was substantial, since the food was worker-oriented and copious. The ferry crew offered many choices of calorie-rich food, and one might certainly eat less than is allowed. Breakfasts were always enormous, and as the English say “one may gain a few pounds, with the gruel-ing exertion”. Folks could walk off the increase by use of the passenger deck at a rate of 8 rounds/American mile, providing in addition a watch for tsunamis. More likely one would see white-sided dolphins, humpbacked whales, and pinnipeds (seals, sea lions, and walruses). Occasionally there were hundreds of the dolphins, where salmon were excursioning toward their spawning grounds. It seems that Life is more vigorous and active, whenever the waters are cold- counter to one’s intuition. All life is aggressively expanding in this cold water environment (40-50 degrees temperature), and there is food for all- including Man. The societies flourishing here had no need to fight, but nevertheless they did. Both Haida and Tlingit were aggressive cultures, having more time to plot battles with their easily-obtained food sources of fish, berries, vegetation, and marine mammals. These were stone-age cultures, with no metals or machinery, but they early on developed sea kayaks, war canoes, stone weapons, and leather protection. Gold was not of interest to them, but they did use ornamental stones- such as copper outcrops (malachite and azurite).
Now for my story:
The Malaspina crept stealthily through the Alaskan waters just south of the first port-of-call in Ketchikan, passing British Columbia’s Dixon entrance, just north of the Strait of Georgia and the last Canadian town (where roads access the sea) of Prince Rupert. The fog obscured the archipelago, with an aptly-authorized appellation of Alexander - and only foghorns could be heard in the eerie surroundings near the vague vessel. The lusty crowd peered expectantly toward the supposed shores, but only pea soup could be seen.
This ominous beginning of the transit through Alaskan waters was a prelude of things to come- there would be no gaily-clad maidens on the shore, no menacing mermaids, nor dancing damsels. These expected entities would exist only in the collective minds of the eager participants; they would have to use imagination to relate the story of the incipience of the Alaskan culture (and that is what you will subsequently read).
The shoreline (whenever it could be seen) became ever closer to the slithering Malaspina, as the Inner Passage was transited. All eyes were focused on the now-approaching rain forest, with all hoping that the Captain was now doing his thing- side slipping adroitly through the churning channel, as he made abrupt turns to avoid rocks and shoals in the path. At times the tide of 8 knots ripped uproariously around the vessel through these narrow channels; this magnified the speed of the diurnal demons, caused by in-rushing waters attracted by the pull of the Moon.
My neighbor in Washington related a story about this very location, via his dad, who had been a lighthouse keeper on the nearby Island of Duke (just south of Ketchikan). It seems that his father lived by his wits, to obtain his food, in this isolated location where only a keeper and occasional supply boats would venture.
One day, between passages of boats which would be warned of the dangers of shallow waters by the man-operated lighthouse, he ventured out into the rain forest to get his weekly ration of venison. He took only two shells for his rifle, thinking that this was sufficient, with the abundant game nearby. However, before reaching a deer, he was suddenly surrounded by menacing wolves- coming into his clearing to attack. One wolf was selected by the pack to bring him down, but this wolf was dispatched instead with one shot. Quickly another worker wolf was sent to bring down the intruder. This one was downed with the remaining shot, by his Dad, and now it was Man against the Pack!
At this point the alpha wolf determined that the intruder would have to be taken by himself, and he charged toward the now firearm-less man, With teeth bared, nostril flaring, and fangs ready for sinking into the flesh of the intruder, the alpha wolf lunged toward the supposedly defenseless prey,. However, the alpha did not reckon for the wit of the quickly-thinking loner. At the last moment, as the leaping wolf hurled toward the lighthouse keeper, the man backed off a half step, grabbed the barrel of the weapon and cracked the wooden stock over the muzzle of the lunging wolf. An audible crack was heard as this most sensitive part of the wolf’ anatomy broke. There followed an eerie howl with paroxysms of pain, as the wolf writhed in misery. Oooo-Uhhhh! I can hear it and feel it in my bones even now, what with a similar event happening to me in Turkey while hunting Hungarian partridges. The other wolves milled around in confusion with the plight of their leader, and after a short period disappeared into the surrounding shrubbery to console the leader- they vanished!
My neighbor tells me that he was given this now-broken rifle, and that he kept it to show the prowess and courage of his Dad, who lived in this now forsaken part of the Alaskan Culture.

But what about the others in the Food Chain? The lower animals, down to the lowly bacteria and Krill- those gulped daily by the whales and others?

SALMON

The fish eyed my lure warily, showing no inclination to envelope it;
He flicked his tail at me contemptuously, knowing that he was in a vastly different world from mine.
In return, I showed great admiration for his adroitness at avoiding my barbeque grill, but there was no social interaction there.
He was indeed cold-bloodied, perhaps with a dash of warmth for the oncoming spawn.
But he appeared to relish this significant time of his life, when he would make tremendous preparation for his moment of bloom and doom. He was at the apex of his existence.
I looked at his majestic form, and exhibited no wariness of my own, still expecting that my vastly larger nervous system would be superior.
We were both looking for an immediate satisfaction of our physical selves- perhaps a bit less slime for myself.
But while my digestive juices were waning, the salmon's desires were at their peak.
Without a salute, he was gone- back to the dark stillness of the deep. Back to primal instincts, but not for myself- I was filled with the joy of sensing my early self.
I remembered the time of my boyhood, when the ancient bowfin or grinnel entranced me.
How he would envelope my dough-ball, slyly pulling down my bait without so much as a signal on my line.
How he would fight, when he found that the treat was attached to a small boy- who would fight back.
But his mouth was soft, as was his entire body, and if you "caught" him, you had to eat him before the bacteria beat you. I would have a fire ready on the creek bank, and savor him immediately (or else give this "low class" fish to a similar class).
But not the salmon- he was at the top of the class, and men would fight to master him. He was indeed a champion.
And he remained so, as did the erudite one- the one with superior intellect and empty plate.

Now, I have to tell and retell the story, the story about Life (and Death) in the cold northland. And indeed I will, since it is embedded deep within my psyche. That’s Soul to you uninitiated, or those so old that they have not embraced the new Nomenclature.
Our ship continued to penetrate the dreary wastes of the land of Cold Life- the land where only a younger mortal could endure. Only those who had laid the groundwork from 50 years previously would appreciate the lure of the North- up to the land of Gold. My wife and I had felt that lure at our impressionable age- during 1959, with new statehood for the young area- which now encompassed more land than twice Texas. And it was taunted that if Alaska were divided, Texas would then become the third state in order of size.
We were new graduates from an unmentionable University in Texas, just embarking upon the venture into the life of the ambitious. Naively we made our plans to live off the land in the new State of Alaska. Unfortunately (or fortunately, viewed from the prism of practicality) we lost Heart after finding that only the US Government ran everything of importance there in those days. This took away all of the Spirit of Adventure, and doomed the effort to embark. Alas! That was the termination of the trek into the new Life of Promise!
And now (and only now) have we returned to the land of our dreams- now that the fires of Life are most extinguished, and the Testosterone Fuel is low. Now we can see the whole Entity- from the Porthole!
Further along the present voyage, we stopped at a port, where we could find a stream making its circuitous route down to the sea. One where salmon could make the reverse journey, one where Eagles, Grizzlies, and Osprey lurked- where the slightest deviation from the proscribed plan was doom for the Salmon pregnant with Life and Fat for the tortuous journey.
We began to see the muscular fish all aligned in the creek- all waiting, waiting for their mate, and for their Doom. These were Humpies (pinks) and Chum (dog salmon), who were not the best eating, but who would be relished by the waiting predators. If they could just outmaneuver the ever-waiting bears and eagles, for just a few days, they could disgorge their next generation, and then they could all die in peace, They could die for refurbishment of the rain forest, while tending the fertilized caviar, placed in shallow gravel beds. O’ just give them time, then their flesh could carry on the Divine Order!
The Order had already anticipated this orgy, and sufficient salmon had survived to the point of new birth, that the ones sacrificed to predators were minimal. The species could be successfully re-generated, with just half of those making this important journey having been fortunate enough to disgorge and fertilize. Life was assured!
Grizzlies and Eagles began to gorge and do their own survival routine, by using the resources of the dead and dying fish. Life was good, for both the higher animals and for the Salmon species, with the roe having been successfully planted in the gravel beds. Man could feel psychologically good also, for Not having interfered with this ancient order of things.
This is part of my Story of Alaska- the land of Gold (and Ghouls).

Slicing through the Tongass (Elderhostel, Malaspina, Sept 5-12/06

O’ my heart’s ever young, as the soggy trap’s sprung,
On the prowl to Lynn Canal- through the Tongass.
But you gotta lay waste all your plans to stay chaste,
When you feel the appeal of the Tongass.

For the Polaris North Star is never quite far,
When you’re verdure for the lure of Alaska;
When you re-live the days of the fifty-nine craze,
With a scheme and a dream of Alaska.

For the trek was not rational
To heed the mighty Need national
And head for a new state of mind.
But all Youth will eschew
The strong Drugs and sly Brew
Of their Elders, who succumb to the fashionable.

Now my years are seven-seven, and my Sourdough’s leaven
With the lure and the cure of the Tlingit.
But once more I stow gear, while abandoning the Fear
For a new state of mind, and likely dubious find (just a trinket).

O’ the hidden midnight sun, where the Muse has just begun
To lure me back, to an old squatter’s shack- in the Tongass.
Where I’m once more in my prime, livin’ a heady simple Time
Of Siskine- a river scene- in the Tongass.

\ Harold L. Overton

Monday, April 23, 2007

EarthLore and Gold in the AZ desert



People finding valuable minerals, such as Gold, are usually those who know that these are found around anomalies. They usually don't read much Geological Literature (not because they spurn such "erudite" treatises, but because the treasure is found not by theory, but by field work). A likely anomaly is that where the rocks tell you that the circumstance is not normal. This could be simply a mineralogical change, a geochemical, thermal, or geophysical abnormality. These are easily tracked in the field, such as in my field of study- a change of resistivity or conductivity (the reciprocals of each other), abnormal electrical potentials, or sudden changes of the fracture orientation in the outcropping rocks.
Above is a recent find in a desert wash, which has been rolled around a bit, and is therefore only a hint of Gold nearby. It was not predicted by any geologist, but was found by someone with a practiced eye. To find out more about this intrigue, refer to the websites for hikes in the SW shown on the right side of the BLOG. HLO