Coal Pits Creek (S27 & 34 T41S R11W, 2/16/05)
 
1.At the paved road 9, we can see Pleistocene gravels, fairly well cemented, and a rough 
age can be determined by the strength of rock (metal hiking pole required); so purchase 
yourself a long golf iron from Deseret Industries, for $1, and cut  off the driver just above 
the wide section of the pole;
2. One can familiarize with Imbrication, which shows the direction of stream flow in 
ancient gravels, similar to shingles on a roof and downhill flow;
3.There is a large basaltic flow which has moved down the pre-existing wash, and one 
can estimate its age. If so, we will get an idea of the direction with time of the volcanic 
emissions moved in the Pliocene- Recent age. In AZ it has already been noticed that the 
vulcanism started about 30my ago and  moved generally westward with time;
4.One can see flat layer-cake beds of the C.P. giving way to dipping beds toward this 
west side. The basalt uplift has created distortions in this monotony;
5. One can study the young gravels (conglomerates, which mostly do not seem to 
occur near Hurricane, due to the rapidity of uplift of the Hurr-fault).  Watch the contact of 
the black basalts over the Red Beds of the Mesozoic all around the Hurrticane-ST.George 
area as you drive on your weekly errands- there is a clean contact between most of them- 
no gravels, soil layer, or basal congolomerate, as is the case at Coal Pits wash. 
Questions:
a.Why is the C.P. so flat and monotonous (except for erosion), compared to the 
Hurricane-ST.G. outcrops, where anticlines, faults, distortions, and other geologic 
anomalies occur?
b.Where will the next cone of the St. George volcanic field occur? Vocanic patterns have 
a great deal of randomness, but there exists a general trend- Notice that the youngest is 
north of Snow Canyon, where the crater has not been breached (probably < 5000 years 
age).
 
Coal Pits Canyon (S34 $ 27 T41S R11W, 2/16/05
Conclusions:
a. Proceeding north on the east bank of the C.P. wash, Quaternary conglomerates are seen 
on the east side of the wash, just at the entrance  gate. These include boulders, which are 
sometimes basalt, that are rounded. Although the color is that of sandstone, it is obvious 
from the large basalts amounts, that a volcanic dam has been breached just a mile or so to 
the north, and the basalts have been carried down by a flood. The strength of the 
cemented sandy portion, as noted by a punch test, is believed to be Pleistocene. More on 
this method of age determination later, but for now, sandstones must be compared to 
other ss., not to shales or limestones. The cemented portion- grains of sand between the 
cobbles and boulders- are the binder for the whole conglomerate, and must be put in a 
frame of reference for comparison with other cemented sandstones. The hardness of the 
cemented grains is seen to increase with time, all the way to quartzites in the early 
Paleozoic or Precambrian time.
b. Proceeding north past the immediate Qal (Quaternary alluvium) outcrop, the 
conglomerate can be seen to dip down to the north, opposite to what should have been the 
original orientation. Hence there has been uplift in this area, since the dam breaching  and 
gravel flow. There appears to be a small east-west fault cutting the conglomerate in 
Section 34, not noted on the Park geologic map. After this location the bedding thickness 
becomes thinner to the north, finally disappearing in S27. This disappearance would 
coincide with the original lava dam blocking the lake sediments to the north. A vent of 
the original volcanics occurs at this location also, on the west side of the creek, with 
upright stock, rather than the horizontal flows seen elsewhere. This vent must be the 
youngest of the local flows, according to the blockage and lake sediments placement. 
When this dam was breached, youngest conglomerates would have moved to the south. 
Further evidence of the dam occurring at this location exists at the hill to the east, where 
tephra or tuffaceous sediments indicate a blockage from east to west. To the north of this 
supposed blockage, the size of  boulders and cobbles become smaller, and finally there 
are lake terraces near this lava outlier.
c. A N-S fault exists on the east side of the creek, in S 27, causing sediments in the 
Triassic to dip down to the west, although the Park Map indicates downthrown to the 
east.
d. Most of the field observations support the idea that Crater Hill, in S 21, is the younger 
of the nearby stocks, since the basalt flows to the south seem to be  more rounded 
(eroded), and have more weathered sediments in the small tributary at the base there.
 
Formation of Limestone, Calcite, and calcareous cement
 The conglomerates found in the Zion Park pose a problem in determining just how sands 
are cemented, to increase their strength with time. It is quite commonly noted that 
unweathered sandstones (and somewhat for limestones, as well) have compressive and 
shear strength which increases with geologic age, finally forming quartzites in the 
Precambrian. This is usually laid off onto the thought that compaction has caused the 
strength increase. However, in the Zion Park conglomerates, there has been essentially no 
increase in overburden on the gravels, there only being some 1 my. or less of time 
involved and no later deposition-overburden, only erosion. So the cementation must not 
be due to overburden or compaction. 
 How exactly does cementation occur in sediments? We'll take the case first as to the 
origination of limestones and calcite, in general. It is noted that limestones do not occur 
significantly in the stratigraphic column, until late Precambrian time, and then in 
stromatolites, and organic deposits. There are large occurrences of  ls.in the  Paleozoic, 
somewhat  less in the Mesozoic, and mostly only fresh water ls in the Tertiary. My 
observation for the present is that the larger beds are forming only in marine conditions 
now as in the Bahamas and Great Barrier reefs and banks. The one looked at close up is 
the case in the Gulf of Mexico and Bahamas. This seems to be inorganically-formed, but 
on close inspection is due to organics also. 
 River systems such as the Mississippi, bring calcium  preferentially (of the cations) to 
the Gulf, where they are taken out of solution by life to form shells and other insoluble 
entities. Currents carry them to the deep Gulf, where they die and sink of their own 
weight. In the deeper waters, they encounter higher pressures and lower temperatures,  
increasing the solubility of limestone and calcite, causing them to be incorporated into the 
flow out of the Gulf into the Gulf Stream. When they are forced out of the gulf, they rise 
to lower pressures and warmer temperatures, both factors causing the solubility to 
decrease. They drop out as oolites and other limestones in the Bahama Banks. This might 
seem to be inorganic, but the critical feature is that organic life has caused them to 
become fixed as a limey material in the first place (if they become fossiliferous limestone 
after that, the relation would be more easily seen). It appears that Life is the critical 
element in the formation of all limestone, and CO2 from the atmosphere is the other 
dominating feature. With time the atmosphere becomes less CO2 dominating as it is 
taken up by Life forms to form limestone, while limestone deposits become prominent in 
the Paleozoic (tying up the Ca and CO2,- which had dominated the atmosphere). When 
the CO2 is largely deposited in organics (coal and limestone, as in the Paleozoic until late 
Permian)), the atmosphere not only became more oxygen dominated, but the waters 
become less acidic (loss of carbonic acid from the atmosphere) causing cherts to 
precipitate in the Paleozoic sediments, where there was a higher solubility of silica 
previously.
 Now take the case of hardpan, or caliche; this case occurs mainly near the ground 
surface, in desert conditions, where  acidic (carbonic acid in rain) precipitation puts salts 
deposited on the ground into solution. This precipitation percolates a short distance into 
the porous soil, and later desiccates, leaving its minerals behind. It is not entirely 
calcareous, but depends upon whatever salts are available, that are readily soluble. 
Rainwater is somewhat acidic, so readily dissolves the calcium compounds at the ground 
surface. This can happen for the case of the young conglomerates noticed near Coal Pits 
Creek. The only unanswered feature is what causes them to become stronger with time.
 The pressure of rock grains can increase the solubility of calcite, but this would be in the 
category of compaction. It must be that Life again plays a part in regulating the 
incorporation of calcite into the pore space. But T, P must also play a part. I notice that as 
one measures the presence of stringers of limey material in deep oil wells, increased 
temperature causes increased hard streaks to occur (in vertical logging presentation). 
With depth, the increased T should decrease the solubility of limestone, and this would 
add calcite to the pore space to harden the sandstone. However, as the well is drilled 
deeper into overpressure, these streaks disappear. This is because of the increased 
solubility of calcite with increase of pressure. So it seems that the interplay of T and P is 
a decisive factor in precipitation of calcite around sand grains to cause them to become 
stronger with temperature. But what about Time?
 Time and organic influence proceed together. That is, the organic intertactions proceed 
with time. Can it be that bacteria, which operate in the soil, interact similarly in the deep 
sediments- as in oil well locations?
 I patented a process, which allows the making of a slurry of oil well cuttings, for 
subsequent presure filtration, to inspect the contents of shale cuttings. I found that there 
was a regular change of the ions in the cuttings, whenever an organic deposit was 
approached. The first thing noticed was that the color of the filtrate from the slurry 
became yellow, then gold and finally amber, upon approaching an organic zone in the 
earth., The color was from lignins and tannins. Later, I did the same experiment with 
garden soil, and found a similar result. Well treated garden soil produced an amber 
filtrate, coinciding with changes in the CO2 profile (or calcite solubility). It appears that 
again the organics- in this case living organisms- are controlling the deposition of calcite 
or limestone. It must be that increasing calcite cementation of sand grains is being 
controlled by living organisms- even in the depths of the earth. This is somewhat 
confirmed indirectly, when  one notices that bacteria or other life form is reducing sulfate 
to sulfur at depths of 3000 feet over salt domes.
 Summing up, The cementation of sandstones, with depth and time is fixed as follows:
1. Cementation starts at the ground surface for loose gravels and sand, caused by a 
caliche-like deposition around the grains, caused by dessication of flowing water- which 
leaves its load of minerals in the shallow sands.
2.As the sand is buried deeper, the dumping of cementing agents proceed with time, by 
rain percolation, until there is no more vertical permeability;
3. With increased burial, the temperature (which increases about 1-2 degrees/ hundred 
feet in the crust) causes increased precipitation of CaCO3 around the grains, in the pore 
space of the sandstone; and
4.Strength of sandstone will increase with depth, as calcite precipitates around the grains.
5. In unusual high pressure zones in the earth (called Geopressure), this cementation of 
the grains will decrease as the solubility of  previously deposited limestone increases.
 But how about a conglomerate sitting at the surface of the earth, such as the one in Coal 
Pits Canyon?
 The caliche-type depositin of cement in sands will increase with time, and be 
accentuated if there is bacteria or other life to cause precipitation of the limey material 
between the grains.
 
 Harold L. Overton