Virgin R., below Hurricane basalts S20,28,29 T41S R13W                                 3/23/05
 
 This area can be accessed at the east end of paved 600N, in Hurricane Sky Mountain golf 
course, walking north along the fence there.
 The Gould canyon is reached initially (just before emptying into the Virgin), showing 
that there are two basalt flows on the north side of the canyon, whereas 3 flows are seen 
in the south wall. This Gould canyon drops precipitously at the end of the golf course, 
at least 50 meters. The additional basalt flow on the south side originates at the Sullivan's 
Knoll (older than the 10,000 year cone), whereas the deeper flows originate from the east, 
in the city limits of Hurricane. Below the lower basalt flow, there is a layered rock, 
appearing to be a meter thick sandstone- flat and almost level, definitely not conformable 
with the underlying Jn- but it could be a grainy tuff; the walls are vertical and could not 
be reached on this hike.The lower and middle basalt flows have been almost peneplaned 
before the upper layers were deposited. This relates that significant time intervened 
between the three basalt flows; all three have cones which occurred in later stages of 
vulcanism (compared to the basalt flows).
 The middle basalt flow terminates against a hill of Jn (fossil dunes, from the 
crossbedding), and immediately below this Jn, there is a flat and almost level 
conglomerate, Pc (Pleistocene conglomerate), at a base of 2830 feet, with top of 2880 
(compare this with the occurrence of Tc, near the town of Virgin, where the elevation 
was 3823 feet at the present conglomerate top). Hence there was a canyon present in the 
Jn to the east in Pleistocene time, which allowed a swift current to carry basalt boulders 
to a large valley where the large meander now occurs. The current dropped off in this 
valley and allowed a wide deposit (about 300 meters) of Pc to accur. This conglomerate 
is mostly basalt boulders initially, but becomes more sand-colored and contains smaller 
boulders and sand to the west (within 200 meters). Looking to the east, at the Hurricane 
cliffs, it is obvious that the basalts lying near the top of the rim of the Hurricane fault 
have originated from the same volcanoes as occurred in the Hurricane city limits; these 
basalts were banked against the old cliffs, showing that there was a fault scarp at the 
initial deposition of basalts, about 30 meters in height.
 In the meander, which is horseshoe shaped, the origin does not seem to come from large 
fractures, although an obvious fault occurs in the middle of the horseshoe turn, in the Jn 
on the west side of the river, running NW-SE. Fractures on the hogback to the NW, on 
the west side of the river, also run NW-SE. However, the fault points to a large ravine on 
the south side of the Virgin, where the fissure makes an abrupt re-orientation to the N-S.
 The large meander now lies deeper than the 2830 Pc, and it could be that the rise of the 
C.P. has initiated a swifter flow which has cut through the Pc and found some deeper 
meander which occurred in the Jn from earlier river flows. This appears doubtful, since 
the Jn has been down-cutting since Eocene times, and it is not likely that there were 
canyons in Jn times.
 The reason that a large horseshoe-shaped meander occurs lower in elevation than the 
Pleistocene conglomerates Pc is not apparent. Why the river would move from a 
floodplain toward the west, away from the shortest course is not yet solved. I will remark 
on this feature, after a few more forays into the canyon. In the meantime, I will try to 
answer the following questions:
a. If large meanders represent lazy streams, in  old age river flows, has there been a time 
since Pc, when the Virgin was not downcutting, but had a slow flow?
b. If there was a slow river flow, why is the river now much lower than the Pc (20 meters 
or so)?
c. Can there have been a disruption of the large valley flow, which was depositing Pc, 
such as with a fault dropping the stream bed on the west side, causing the stream to divert 
there?
d. Is the extensive vulcanism the reason for the large canyons occurring in the Virgin,all 
the way from the town of Virgin to this investigated meander (if so, the course of the 
river would have been determined by the location of the basalts)?
e. Remembering that there was a disruption of the basalt on the north wall of the Virgin, 
immediately west of the town of Virgin, it appears that other uplift has occurred on the 
west side of the Hurricane fault, separately from the uplift on the east side. Block faulting 
in the same area, of Mesozoic redbeds, not in the principal directions of NE-SW or NW-
SE, occurs in the city limits of Laverkin. Are these anomalies due to the local extrusions 
of basalt?
 
 Here are findings, not arguable:
1. Virgin river flow now occurs at the border of the latest basalt flow, but cuts through 
the older basalts;
2. There is a fine-grained deposition of sediment or tuff layer, at the base of the oldest 
basalt flow;
3. Gould Canyon has walked some .5 km upstream, leaving a box canyon at its dropoff 
location;
4. All 3 basalt flows had cinder cones associated with them in their late stages;
5. The Pleistocene Pc starts just downstream of the Gould's canyon mouth, and is first 
mostly large basaltic boulders (up to 30 centimeters), and then increasingly sandy and 
smaller boulders to the west. Pc continues to the north for 300 meters or so, giving way to 
the present flood plain fo the Virgin- which lies atop Jn;
6. The Pc cementation is like concrete- much stronger than expected for this age rock- the 
Kaibab limestone clasts, which are numerous, may yield much more calcareous cement 
than clasts from the Mesozoic, which is mostly silicate;
7. Faulting and fractures in the Mesozoic redbeds on the west side of the river run NW-
SE, not in the directions of the path of the Virgin River. The expected fault occurs 
midway in the horseshoe turn, leaving scree and a saddle in its path- it points to a 2 meter 
fissure on the south side of the river; and
8. Although the Jn below the Gould's Canyon wall on the north side is fairly flat and 
covered by thin sediment, it is generally hilly and irregular on the north side of the Virgin 
in contacts with basalt (it even blocks the basalt flow in some cases). Harold L. Overton