Non-sedimentary Structures in the Drift
The unconsolidated sands and gravels of the drift with patterns of
cross stratification can be explained as a product of a disintegration
process. There are several non-sedimentary features associated with
these sandy layers. Examples are the presence of lenses and balls of
coarse material in fine sands, or lenses and balls of fine sand in
coarse gravel layers. These are unlikely to have been produced in
sedimentary environments, particularly when the sand balls have a
distinct composition, or concentric structure, which points to
concretionary processes. The drift also contains disintegrated boulders
that could not have been transported to their positions, concretions,
vertical pillars that may become eroded into hoodoos at the surface,
Structures such the sand dike shown below are evidence against a
sedimentary interpretation of the patterns of cross strata. This
structure is called a "clastic dike" but that terminology implies an
interpretation that the writer rejects. "Clastic" suggests that the
material has been transported and deposited in streams. The so-called
clastic dikes are usually attributed to injection of sand into a
fissure from either above or below. That seems unlikely here, because
of the unconsolidated nature of both the sand matrix and the dike
contents. The sedimentary interpretation of patterns of cross
stratification of the coarse material in the dike, usually attributed
to deposition in fast currents, is the real root of the problem.
|The photo at left shows
details of part of a clastic dike containing coarse sand with
horizontal cross strata and pebbles. The dike is on the left, and the
matrix of fine cross stratified sand on the right. All the sand in the
photo is unconsolidated. Along the dike walls there are thin films of
clay or silt sized material. The total width of the dike was about 0.5
m. The dike was observed in a gravel pit near Campbellville Ontario,
about 2 km east of the Guelph line - Highway 401 intersection.
Problems with the conventional interpretation:
- A fissure deep enough to contain the dike could not form in
- Conventional explanations of clastic dikes say build up of water
pressure below and its sudden release during an earthquake forcefully
injected fluids and sand into a fissure through the overlying rock.
not work for the unconsolidated sandy material in this case because it
and the high fluid pressures in underlying rocks would not occur.
- If earthquakes are invoked for the formation of the fissure, the
disturbance would destroy the patterns of stratification in the
surrounding sand and gravel, yet those patterns in the sand remain
intact and undisturbed.
- There is no plausible mechanism for injection of material with a
different texture from above or below.
- Since they pinch and swell and walls are not parallel, the dikes
are not explained merely by formation of a fissure that was infilled.
- Patterns of cross strata in the coarse sandy material within the
dike are thought to imply fast currents, but such currents would tend
to erode the sand enclosing the dike, and there is no indication that
- Directional features around pebbles within the dike are absent,
indicating no currents were involved.
- Distinct layering of coarse material does not indicate a former
sedimentary environment in the dike, as the presence of pebbles on a
stream bed generates turbulence resulting in indistinct layers and
directional features, such as current shadows and tails of sediment on
the lee side of obstacles. Such directional features are absent.
Explanation as a non-sedimentary structure
The formation of vertical dikes containing stratified sand and gravel
is a serious problem for conventional geology but they are easily
explained by the writer's in situ
disintegration interpretation. In the former environment of rapid
removal of overburden by fast currents, the sediments were compacted
and rock was lithified. At the surface the rock was disintegrated and
converted to sand and gravel, with the patterns of cross stratification
evident in sandy layers. This pattern records the progress of the front
of alteration as it penetrated the rock. In the case of the dike
illustrated above this process disintegrated the rock between two
adjacent joints, forming the coarse stratified sand and gravel between
the joints. Subsequently the surrounding rock was also disintegrated.
Clastic Dike in a
Bedrock Rafts and
Megablocks in the Drift
Peterson, G.L. 1968. Flow structures in sandstone dikes. Sedimentary
Spencer, P.K., and Jaffee, M.A., 2002. Pre-Late Wisconsinan Glacial
Outburst Floods in Southeastern Washington-The Indirect Record.
Washington Geology, vol. 30, no. 1/2, July 2002
Figure 5 in the above paper shows a compound clastic dike in the
Touchet Beds. (See p. 10)
Cox, D.E. 1978. (Discussion) Re: Roth: Clastic Dikes (ORIGINS
Roth, A.A. 1992. Clastic dikes in the Kodachrome Basin. Origins
A rebuttal of the above paper is presented in:
Morton, G.R., 2002. Why Clastic Dykes Don't Indicate a Global Flood
Copyright © 2006
by Douglas E. Cox
the Glacial Theory