Virgin (Laverkin Overlook) S25 T41S R12W Hiway 9, going east from Hurricane town, before entering the town of Virgin, at the junction of a gravel road labeled Virgin Overlook, has a trail near the dead-end, going into the Virgin canyon. At the rim, one can see the angles in the river, making right turns, then left turns, along major fracture planes (4 altogether). These fractures and possibly faulting are parallel to each other, oriented at 20 degrees east of north, and the orthogonals are almost NW-SE, or 290-110 degrees from north ( near the regional fracture orientation for most of the southwest); finally the river exits at the town of Laverkin, on another almost NW orientation). Scan the Hurricane 7 ½ minute topo, to see these almost perfect orthogonals in the river course. These are not parallel or perpendicular to the Hurricane fault, rather represent the stress pattern for the period up to about 2 million years ago, now superceded by a N-S fracture and fault orientation. Jack Gubler and I retraced the river, but at the canyon rim above on the north side, to note that there are dominant 20- 200 degrees from north fissures and fractures, which evidently determined the course of the river, allowing it to exit the uplift to the west. This exit encountered some 800 feet of uplift of the Kaibab Limestone to the west, but the fissures and fractures allowed rainfall to stream toward the east- until encountering the streams exiting the Zion platform, attempting to pond. The town of Virgin sits in a bowl, except for the Virgin outlet- which has eroded the uplift to the west. Looking at the fractures from the canyon rim, it is clear that the 20- 200 degree fracts are dominant- forming deep fissures and slumping along this direction. These fissures are parallel to the present Virgin River, spalling and slumping into it. The perpendicular fracts, oriented 295-115 degrees from north, are noticeable, but not continuous as are the dominant ones to the NW. Note: this direction is not quite NW-SE (the usual orientation for most of the western US), but it is expected that the Hurricane fault and previous weaknesses have distorted the usual west US NW-SE pattern. Looking at the Hurricane topo, the orientation of the fracts changes, as soon as the river exits from the Hurricane fault. Several straight line portions of the river orient 340-160 after the exit (to the west); the orthogonal to these is 70-250, which is about the orientation of the Virgin anticline and Pine Valley Mtns. Hence it seems that the Hurricane fault is the expression of a fundamental stress change between the C.P. proper and the transition zone (beginning of the basin and range province) The river has broken through the uplift along the Hurricane fault, even though there is a slight uplift on the east side of the fault (800 feet), and the beds are tilted down to the east. The Kaibab, Pk, limestone is omnipresent, and forms a fairly flat landscape until close to the canyon- it is not level, even in the subsurface formations- presenting a hinge at one of the orthogonal changes in the fracture pattern. The fractures have allowed the river to exit, even though the landscape tilt is opposite to river flow direction; likely, there has been stream capture of a gully exiting the hurricane cliffs- allowing the effluent from the Zion platform to exit, after uplift. Jack showed me where there is a Pleistocene- Miocene conglomerate just west of the town of Virgin, sitting on top of Mesozoic red beds; this indicates that there was significant flow of the Virgin in times of a few million years before present, when flow was large, coming out of the Zion platform, hence the rise of the C.P; may have happened several times(intermittent uplift). There is now 800 foot elevation change to the river, from the present cliffs. Halfway down the faint trail, there are voluminous fossil brachiopods, gastropods and some crinoids. Near these, there is the best chert display I have seen- forming some 25% of the rock; these cherts run in parallel bedding planes, and some of them can be seen to have been formed in shell molds. They are generally limonite colored, with some having manganese or desert varnish coatings. The ri The right angle turns (4 altogether) arrangement of the river course means that the old NW-SE fracture pattern was still dominant when the river broke through; this is thought to be some 2 million years ago (by me), but will be a date to be improved as more information is gleaned from the Hurricane fault. The Hurricane fault orientation is N-S, and the Pine Valley- Virgin anticline orientation is NE-SW, and this third orientation is thought to be the dominant one immediately preceding the present stress-fracture pattern. The present one is seen in the Verde limestone (of 5 my.age), in central AZ. and in several N-S river courses in AZ and New Mexico (Rio Grande, lower Colorado, and Verde Rivers). The present stress system could be influenced by the nearby basin and range, which trends N-S, since the Hurricane fault is in the transition zone (as it is in AZ). But this does not mean that internally in the C.P. the external stress system is the dominant mechanism for movement- conversely, the rise there seems to be a universal heat uplift, as evidenced by the massive sedimentary blanket yielding temperature gradients in most oil well boreholes, some twice what is noticed in the gulf coast (1.6 degrees/hundred feet vs. 1.0). This high temperature gradient does not necessarily mean that the heat flow is unusually large, since the blanket retains the heat, and this may be the dominant reason why the C.P. is rising (extra heat retained would make the plateau thermally expand more than its neighbors, as is the case- except for occasional extrusions and intrusions noted on the plateau). Down Downstream of the Hurricane fault, there are a few meanders, indicating that the stream was an old age one (similar to the Mississippi River), prior to the renewed uplift of the Hurricane fault. We will study the river, east of the fault, to see whether there are any meanders there (Virgin topo). This will yield a conclusion about the flatness of the terrain, before the river began to cut down through the Hurricane fault. Tentatively, there are some meanders to the east, indicating that the whole river was old-age in this pre-uplift phase (this means that the land west of Zion Park was almost flat and level). Incidentally, I have been to the original meander namesake (eponymous)- the one in Turkey, near Ephesus. The original name was Menderes River, a family name for one of the recent Premiers of Turkey, and it has been anglicized or corrupted to the term meander. Meanders occur in rivers which have little stream gradient, so that the stream makes large diversions (ox bows) from its straight line course. This is termed "old age", since the land is flat, the river is sluggish (like an old man), the water is muddy, and the fishing is for the elderly (no invigorating rapids or white water). T dThe e The erosion rate for the Virgin River near the Hurricane cliffs may be calculated, by taking the elevation difference from flat country above the river to the river level-- about 800 feet- and dividing by the time since the cliffs last rose. This date is probably about 2 my., but we will attempt to find it more acurately, by measuring the distance cliffs have "walked" in other canyons and multiplying by 600 years/foot- which is the rate measured in AZ for the Mogollon retreat near the House Mt. volcano, formed against the rim some 13 million years ago, and now has "walked" a measureable distance (to yield the 600 yr/foot figure). The orthogonal The pattern the river makes on its way out of the canyon is a dead give-away that the river has eaten into the old orthogonal NW-SE & NE-SW orthogonal fractures generated in the last 10 my. The fractures are not quite exactly NW-SE as seen in the Verde Valley. But there are a number of other uplifts here also (and irregularities such as the oscillation of the Hurricane cliffs trend), tending to "throw off" the orientation of the old stress system. There could be faults oriented in this NW-SE direction, following the fractures, but the only thing I can see from the cliffs is the hinge in the stratified beds higher in the canyon walls. This hinge trends N-S, similar to the hurricane cliffs; it is accentuated by a saddle to the south to which it points. Look at the 7 ½ minute topos to determine your interpretation to this fracture-fault system. We will revisit this river mouth whenever we have other cliff severances, with which to compare. I think that we will be able to pull ourselves up by our bootstraps, as the spring season proceeds. If not, I will start the whole thing over next year- 2006. The assumptions will be the following, to calculate Hurricane uplift time and erosion rates: a. The landsca a, The slope was fairly flat and almost level, when the Hurricane cliffs began to rise the latest time, as evidenced by the meanders upstream and downstream of the river exit; b. The right ang b. The right angle turns in the river course, just before exiting the plateau, are due to open fractures in the flat country at the time and similarly to the orthogonals (ones at right angles); c. The pattern which the river made and is still making, was pre-determined by the old-age system, and the uplift was so rapid, that the river was unable to straighten itself with regular flooding; d. The climate a c. Upper Mesozoic and Permian age rocks are nearly the same here as in AZ, where the retreat rate of 600yr/ft was measured, so that the rate can be assumed to be the same; and e. The Uplift of the Hurricane cliffs is continuing at an average rate, similar to what was in effect as soon as the last uplift started- this assumes no acceleration, which may be the largest source of error. Sources of error for the above calculations include: 1. Vulcanism during this period may have yielded temporary cessations of the uplift; 2 Erosion may be accelerating as the uplift gets larger; 3. The long term droughts and wet spells may have changed drasticly with time- yielding drastic changes in water available to downcut the river bed; and 4. The more rigid limestone, as compared to the thin dirty beds deeper in the column, would have had a small erosion and downcutting rate compared to that now. Lurking below all of this is my assessment that the Colorado Plateau, as evidenced by my study of its SW edge in AZ, did the following: First, the Pacific plate moved NE-ward under AZ and NV, starting with the Nevadan orogeny in the Jurassic; Secondly, the plate continued, resulting in the Sevier compressional entities noticed in Utah, in the Cretaceous; Thirdly, the plate movement terminated in the Rocky Mountains, causing erosional effects all the way into the Eocene, in Colorado and New Mexico. This initial uplift was only some 1000-2000 feet. After this Laramide episode ceased, there was a lull, until the Oligocene, when the dogleg in the Hawaiian- Emporer Seamount indicated that the Pacific plate started wrenching to the NW (about a 60 degree turn); Stresses changed from compressional to extensional during this period, and vulcanism commenced. Where vulcanism could not be relieved- which is the greatest part of the C.P- the Colorado Plateau thermally expanded up to its present elevation of 6000 feet (almost all of the vulcanic _expression is around the edge of the C.P). Finally, This wrenching continued until about 2 million years ago, when the stress re-oriented toward the north, causing shear of the Verde limestone and edge of the Colorado Plateau, as in the Hurricane fault. Harold L. Overton Virgin (Laverkin Overlook) S25 T41S R12W Hiway 9, going east from Hurricane town, before entering the town of Virgin, at the junction of a gravel road labeled Virgin Overlook, has a trail near the dead-end, going into the Virgin canyon. At the rim, one can see the angles in the river, making right turns, then left turns, along major fracture planes (4 altogether). These fractures and possibly faulting are parallel to each other, oriented at 20 degrees east of north, and the orthogonals are almost NW-SE, or 290-110 degrees from north ( near the regional fracture orientation for most of the southwest); finally the river exits at the town of Laverkin, on another almost NW orientation). Scan the Hurricane 7 ½ minute topo, to see these almost perfect orthogonals in the river course. These are not parallel or perpendicular to the Hurricane fault, rather represent the stress pattern for the period up to about 2 million years ago, now superceded by a N-S fracture and fault orientation. Jack Gubler and I retraced the river, but at the canyon rim above on the north side, to note that there are dominant 20- 200 degrees from north fissures and fractures, which evidently derermined the course of the river, allowing it to exit the uplift to the west. This exit encountered some 800 feet of uplift of the Kaibab Limestone to the west, but the fissures and fractures allowed rainifall to stream toward the east- until encountering the streams exiting the Zion platform, attempting to pond. The town of Virgin sits in a bowl, except for the Virgin outlet- which has eroded the uplift ot the west. Looking st the fractures from the canyon rim, it is clear that the 20-200 degree fracts are dominant- forming deep fissures and slumping along this direction. These fisssures are parallel to the present Virgin River, spalling and slumping into it. The perpendicular fracts, oriented 295-115 degrees from north, are noticeable, but not continuous as are the dominant ones to the NW. Note: this direction is not quite NW-SE (the usual orientation for most of the western US), but it is expected that the Hurricane fault and previous weaknesses have distorted the usual west US NW-SE pattern. Looking at the Hurricane topo, the orientation of the fracts changes, as soon as the river exits from the Hurricane fault.Several straight line portions of the river orient 340-160 after the exit (to the west); the orthogonal to these is 70-250, which is about the orientation of the Virgin anticline and Pine Valley Mtns. Hence it seems that the Hurricane fault is the _expression of a fundamental stress change betwee the C.P. proper and the transition zone (beginning of the basin and range province) The river has broken through the uplift along the Hurricane fault, even though there is a slight uplift on the east side of the fault (800 feet), and the beds are tilted down to the east. The Kaibab, Pk, limestone is omnipresent, and forms a fairly flat landscape until close to the canyon- it is not level, even in the subsurface formations- presenting a hinge at one of the orthogonal changes in the fracture pattern. The fractures have allowed the river to exit, even though the landscape tilt is opposite to river flow direction; likely, there has been stream capture of a gully exiting the hurricane cliffs- allowing the effluent from the Zion platform to exit, after uplift. Jack showed me where there is a Pleistocene- Miocene conglomerate jsut west of the town of Virgin, sitting on top of Mesozoic redbeds; this indicates that there was significant flow of the Virgin in times of a few million years before present, when flow was large, coming out of the Zion platform, hence the rise of the C.P; may have happened several times(intermittant uplift). There is now 800 foot elevation change to the river, from the present cliffs. Halfway down the faint trail, there are voluminous fossil brachiopods, gastropods and some crinoids. Near these, there is the best chert display I have seen- forming some 25% of the rock; these cherts run in parallel bedding planes, and some of them can be seen to have been formed in shell molds. They are generally limonite colored, with some having manganese or desert varnish coatings. The right angle turns (4 altogether) arrangement of the river course means that the old NW-SE fracture pattern was still dominant when the river broke through; this is thought to be some 2 million years ago (by me), but will be a date to be improved as more information is gleaned from the Hurricane fault. The Hurricane fault orientation is N-S, and the Pine Valley- Virgin anticline orientation is NE-SW, and this third orientation is thought to be the dominant one immediately preceding the present stress-fracture pattern. The present one is seen in the Verde limestone (of 5 my.age), in central AZ. and in several N-S river courses in AZ and New Mexico (Rio Grande, lower Colorado, and Verde Rivers). The present stress system could be influenced by the nearby basin and range, which trends N-S, since the Hurricane fault is in the transition zone (as it is in AZ). But this does not mean that internally in the C.P. the external stress system is the dominant mechanism for movement- conversely, the rise there seems to be a universal heat uplift, as evidenced by the massive sedimentary blanket yielding temperature gradients in most oil well boreholes, some twice what is noticed in the gulf coast (1.6 degrees/hundred feet vs. 1.0). This high temperature gradient does not necessarily mean that the heat flow is unusually large, since the blanket retains the heat, and this may be the dominant reason why the C.P. is rising (extra heat retained would make the plateau thermally expand more than its neighbors, as is the case- except for occasional extrusions and intrusions noted on the plateau). Downstream of the Hurricane fault, there are a few meanders, indicating that the stream was an old age one (similar to the Mississippi River), prior to the renewed uplift of the Hurricane fault. We will study the river, east of the fault, to see whether there are any meanders there (Virgin topo). This will yield a conclusion about the flatness of the terrain, before the river began to cut down through the Hurricane fault. Tentatively, there are some meanders to the east, indicating that the whole river was old-age in this pre- uplift phase (this means that the land west of Zion Park was almost flat and level). Incidentally, I have been to the original meander namesake (eponymous)- the one in Turkey, near Ephesus. The original name was Menderes River, a family name for one of the recent Premiers of Turkey, and it has been anglicized or corrupted to the term meander. Meanders occur in rivers which have little stream gradient, so that the stream makes large diversions (ox bows) from its straight line course. This is termed "old age", since the land is flat, the river is sluggish (like an old man), the water is muddy, and the fishing is for the elderly (no invigorating rapids or white water). The erosion rate for the Virgin River near the Hurricane cliffs may be calculated, by taking the elevation difference from flat country above the river to the river level-- about 800 feet- and dividing by the time since the cliffs last rose. This date is probably about 2 my., but we will attempt to find it more acurately, by measuring the distance cliffs have "walked" in other canyons and multiplying by 600 years/foot- which is the rate measured in AZ for the Mogollon retreat near the House Mt. volcano, formed against the rim some 13 million years ago, and now has "walked" a measureable distance (to yield the 600 yr/foot figure). The orthogonal pattern the river makes on its way out of the canyon is a dead give-away that the river has eaten into the old orthogonal NW-SE & NE-SW orthogonal fractures generated in the last 10 my. The fractures are not quite exactly NW-SE as seen in the Verde Valley. But there are a number of other uplifts here also (and irregularities such as the oscillation of the Hurricane cliffs trend), tending to "throw off" the orientation of the old stress system. There could be faults oriented in this NW-SE direction, following the fractures, but the only thing I can see from the cliffs is the hinge in the stratified beds higher in the canyon walls. This hinge trends N-S, similar to the hurricane cliffs; it is accentuated by a saddle to the south to which it points. Look at the 7 ½ minute topos to determine your interpretation to this fracture-fault system. We will revisit this river mouth whenever we have other cliff severances, with which to compare. I think that we will be able to pull ourselves up by our bootstraps, as the spring season proceeds. If not, I will start the whole thing over next year- 2006. The assumptions will be the following, to calculate Hurricane uplift time and erosion rates: a. The landscape was fairly flat and almost level, when the Hurricane cliffs began to rise the latest time, as evidenced by the meanders upstream and downstream of the river exit; b. The right angle turns in the river course, just before exiting the plateau, are due to open fractures in the flat country at the time and similarly to the orthogonals (ones at right angles); c. The pattern which the river made and is still making, was pre-determined by the old- age system, and the uplift was so rapid, that the river was unable to straighten itself with regular flooding; d. The climate and Permian age rocks are nearly the same here as in AZ, where the retreat rate of 600yr/ft was measured, so that the rate can be assumed to be the same; and e. The Uplift of the Hurricane cliffs is continuing at an average rate, similar to what was in effect as soon as the last uplift started- this assumes no acceleration, which may be the largest source of error. Sources of error for the above calculations include: 1. Vulcanism during this period may have yielded temporary cessations of the uplift; 2 Erosion may be accelerating as the uplift gets larger; 3. The long term droughts and wet spells may have changed drasticly with time- yielding drastic changes in water available to downcut the river bed; and 4. The more rigid limestone, as compared to the thin dirty beds deeper in the column, would have had a small erosion and downcutting rate compared to that now. Lurking below all of this is my assessment that the Colorado Plateau, as evidenced by my study of its SW edge in AZ, did the following: First, the Pacific plate moved NE-ward under AZ and NV, starting with the Nevadan orogeny in the Jurassic; Secondly, the plate continued, resulting in the Sevier compressional entities noticed in Utah, in the Cretaceous; Thirdly, the plate movement terminated in the Rocky Mountains, causing erosional effects all the way into the Eocene, in Colorado and New Mexico. This initial uplift was only some 1000-2000 feet. After this Laramide episode ceased, there was a lull, until the Oligocene, when the dogleg in the Hawaiian-Emporer Seamount indicated that the Pacific plate started wrenching to the NW (about a 60 degree turn); Stresses changed from compressional to extensional during this period, and vulcanism commenced. Where vulcanism could not be relieved- which is the greatest part of the C.P- the Colorado Plateau thermally expanded up to its present elevation of 6000 feet (almost all of the vulcanic _expression is around the edge of the C.P). Finally, this wrenching continued until about 2 million years ago, when the stress re-oriented toward the north, causing shear of the Verde limestone and edge of the Colorado Plateau, as in the Hurricane fault . E-W faulting across the Hurricane fault It is assumed that the faults running east to west across the large Hurricane fault are orthogonal to the main fault. To test this hypothesis, several canyons were investigated, which fit this category. The first one is that for the Virgin River, exiting at the Laverkin town bridge. In this case, there is an uplift of almost 300 meters on the east side of the fault, which any creek will have to surmount in order to exit. The town of Virgin, east of the fault, sits in a topographical basin, except for the Virgin canyon. Virgin canyon cuts through at least 800 feet of lower Mesozoic to Permian Kaibab sediments, in order to exit the basin. The sediments are fairly flat and level at the present town. But there is a gradual uplift to the west, which previously blocked the stream. Equivalent to the exit elevation, there is an outcrop of Tertiary gravels, which sit 2 km to the west of Virgin town, which give a clue to the cutting down of the plateau, for the Virgin to exit. This conglomerate, Tc, contains a single cobble of vesicular basalt, indicating that the age is of the start of fissure basalt (about 1 m y.) or that it is an exotic, giving a false clue. The gravels in the conglomerate are well rounded and larger than sand size (but contain no boulders), indicating that the gradient was low for the old stream. This is not a canyon deposit, since the outcrop is flat and almost level, hence there was a flood plain at the late Tertiary time, Tc, of its deposition, It is possible that the flow was to the west, at the time (probably Pliocene, by the rock strength punch test), consequently there was probably not a significant scarp where the Hurricane fault now exists. If so the rise of Kaibab sediments came later than the Tc, and happened simultaneously with the fault scarp rising. E-W faulting across the Hurricane fault It is assumed that the faults running east to west across the large Hurricane fault are orthogonal to the main fault. To test this hypothesis, several canyons were investigated, which fit this category. The first one is that for the Virgin River, exiting at the Laverkin town bridge. In this case, there is an uplift of almost 300 meters- beds tilted up to the west, including the landscape- on the east side of the fault, which any creek will have to surmount in order to exit. The town of Virgin, east of the fault, sits in a topographical basin, except for the Virgin canyon. Virgin canyon cuts through at least 800 feet of lower Mesozoic to Permian Kaibab sediments, in order to exit the basin. The sediments are fairly flat and level at the present town. But there is a gradual uplift to the west, which previously blocked the stream. Equivalent to the exit elevation, there is an outcrop of Tertiary gravels, which sit 2 km to the west of Virgin town, which give a clue to the cutting down of the plateau, for the Virgin to exit. This conglomerate, Tc, contains a single cobble of vesicular basalt, indicating that the age is of the start of fissure basalt (about 1 m y.) or that it is an exotic, giving a false clue. The gravels in the conglomerate are well rounded and larger than sand size (but contain no boulders), indicating that the gradient was low for the old stream. This is not a canyon deposit, since the outcrop is flat and almost level, hence there was a flood plain at the late Tertiary time, Tc, of its deposition, It is possible that the flow was to the west, at the time (probably Pliocene, by the rock strength punch test), consequently there was probably not a significant scarp where the Hurricane fault now exists. If so the rise of Kaibab sediments came later than the Tc, and happened simultaneously with the fault scarp rising. There are many boulders of basalt scattered around the base of Tc, indicating floods brought some of the surrounding meas basalts down to deposit near the Tertiary conglomerate. These could have at one time been higher in elevation than Tc, or could have flowed around the outcrop after it was eroded down to present elevation. The Virgin River is seen to exit its canyon preceded by 4 well-developed right angle turns in its course. Above these obvious grid-like fracture openings, there exists on the plateau above slumping into the Virgin, on a similar pattern., The slumps are well- developed with orientations along fracture lines, several of which are parallel to each other in a single slump. The linear is on an orientation of 340-160 degrees from north. Whenever the river makes a right angle turn, the slumps (although at right angles to the dominant fractures) do not make such easily seen linears on the cliffs above- conversely, they create blocky fissures, with very little linear manifestations. The fissures in all cases are large- some with widths of meters, with vegetation growing in the soil in them.E-W faulting across the Hurricane fault It is assumed that the faults running east to west across the large Hurricane fault are orthogonal to the main fault. To test this hypothesis, several canyons were investigated, which fit this category. The first one is that for the Virgin River, exiting at the Laverkin town bridge. In this case, there is an uplift of almost 300 meters- beds tilted up to the west, including the landscape- on the east side of the fault, which any creek will have to surmount in order to exit. The town of Virgin, east of the fault, sits in a topographical basin, except for the Virgin canyon. Virgin canyon cuts through at least 800 feet of lower Mesozoic to Permian Kaibab sediments, in order to exit the basin. The sediments are fairly flat and level at the present town. But there is a gradual uplift to the west, which previously blocked the stream. Equivalent to the exit elevation, there is an outcrop of Tertiary gravels, which sit 2 km to the west of Virgin town, which give a clue to the cutting down of the plateau, for the Virgin to exit. This conglomerate, Tc, contains a single cobble of vesicular basalt, indicating that the age is of the start of fissure basalt (about 1 m y.) or that it is an exotic, giving a false clue. The gravels in the conglomerate are well rounded and larger than sand size (but contain no boulders), indicating that the gradient was low for the old stream. This is not a canyon deposit, since the outcrop is flat and almost level, hence there was a flood plain at the late Tertiary time, Tc, of its deposition, It is possible that the flow was to the west, at the time (probably Pliocene, by the rock strength punch test), consequently there was probably not a significant scarp where the Hurricane fault now exists. If so the rise of Kaibab sediments came later than the Tc, and happened simultaneously with the fault scarp rising. There are many boulders of basalt scattered around the base of Tc, indicating floods brought some of the surrounding meas basalts down to deposit near the Tertiary conglomerate. These could have at one time been higher in elevation than Tc, or could have flowed around the outcrop after it was eroded down to present elevation. The Virgin River is seen to exit its canyon preceded by 4 well-developed right angle turns in its course. Above these obvious grid-like fracture openings, there exists on the plateau above slumping into the Virgin, on a similar pattern., The slumps are well-developed with orientations along fracture lines, several of which are parallel to each other in a single slump. The linear is on an orientation of 340-160 degrees from north. Whenever the river makes a right angle turn, the slumps (although at right angles to the dominant fractures) do not make such easily seen linears on the cliffs above- conversely, they create blocky fissures, with very little linear manifestations. The fissures in all cases are large- some with widths of meters, with vegetation growing in the soil in them. E-W faulting across the Hurricane fault The Virgin River is seen to exit its canyon preceded by 4 well-developed right angle turns in its course. Above these obvious grid-like fracture openings, there exists on the plateau above slumping into the Virgin, on a similar pattern., The slumps are well-developed with orientations along fracture lines, several of which are parallel to each other in a single slump. The linear is on an orientation of 340-160 degrees from north. Whenever the river makes a right angle turn, the slumps (although at right angles to the dominant fractures) do not make such easily seen linears on the cliffs above- conversely, they create blocky fissures, with very little linear manifestations. The fissures in all cases are large- some with widths of meters, with vegetation growing in the soil in them. E-W faulting across the Hurricane fault It is assumed that the faults running east to west across the large Hurricane fault are orthogonal to the main fault. To test this hypothesis, several canyons were investigated, which fit this category. The first one is that for the Virgin River, exiting at the Laverkin town bridge. In this case, there is an uplift of almost 300 meters- beds tilted up to the west, including the landscape- on the east side of the fault, which any creek will have to surmount in order to exit. The town of Virgin, east of the fault, sits in a topographical basin, except for the Virgin canyon. Virgin canyon cuts through at least 800 feet of lower Mesozoic to Permian Kaibab sediments, in order to exit the basin. The sediments are fairly flat and level at the present town. But there is a gradual uplift to the west, which previously blocked the stream. Equivalent to the exit elevation, there is an outcrop of Tertiary gravels, which sit 2 km to the west of Virgin town, which give a clue to the cutting down of the plateau, for the Virgin to exit. This conglomerate, Tc, contains a single cobble of vesicular basalt, indicating that the age is of the start of fissure basalt (about 1 m y.) or that it is an exotic, giving a false clue.