A colleague of mine who is a sedimentologist has spent his entire career
studying the Green River Formation just laughs when he hears them referred
to as varves, especially at the cyclical arguments. He has counted varves
in various parts of the basin between two ashfall tuff marker beds that are
basin-wide. In the center of the basin there are far fewer "varves"
between the ashbeds than near the margins of the basin, thus invalidating
the use of these laminae as varves, or at least making them unusable for
cyclical studies. Furthermore a number of careful statistical studies have
cast doubt on the use of the laminae as "varves".
Original publication suggest the possibility of 5 and 11 year cycles
("...by judicious data selection...")in what they viewed mostly as noise at
other scales. Crowley, Duchon and Rhi (1986) in J. Geophys. Res.
91:8637-8647.
Ripepe, Roberts, amd Fischer made astonishing claims for 11 and 5 year
cycles (1991) in J. Sed. Pet. 61:1155-1163.
And subsequently extended their claims in a second paper by Fischer and
Roberts asserting Milankovitch type 20k, 100k cycles (same year) J. Sed.
Pet. 61: 1146-1154.
Neither of the latter appeared to be aware of the paper cited in the
Crowley paper by Pittock (1978) Reviews of Geophysics and Space Physics
16:400-420. In this paper, entitled"A Critical Look at the Long-term
Sun-Weather Relationships"
The abstract reads as follows:
"Many and varied claims have been made over many years for a relationship
between weather or climate and solar variations, notably sunspot cycles.
Those relating primarily to the single and double sunspot cycles (of about
11- and 22-year quasi-periodicities) are critically reviewed in the light
of what is known about solar variations, the observed variability of
weather and climate, and possible physical connections between the two.
Various pitfalls in the application or lack of application of statistics to
the problem are discussed and illustrated from the literature. Following a
survey of the literature it is concluded that despite the great number of
recent papers on the subject, little convincing evidence has yet been
produced for real correlations between sunspot cycles and the
weather/climate on the 11- and 22-year time scales, although evidence for
correlations with solar events on time scales of daus appears to exist.
The state of the literature in this particularly controversial area must
raise doubts as to the prevaling standards of objectivity and critical
analysis in other areas of science as well. Clearly, in the case of
sun-weather relationships, further research requires MUCH HIGHER STANDARDS
OF OBJECTIVITY, with the rigorous and critical application of statistics,
and step by step investigation of hypothetical mechanisms. This criticism
is not addressed to the recent studies of apparently significant
correlations between certain meterological indices and the passage of
interplanetary magnetic sector boundaries; however, the relevance of such
correlations to time scales of climatic interest has yet to be demonstrated."
In the case of the Green River Shale, the coungting of laminae is
particularly problematic, since they are often thin or fragmentary and may
change dramatically over horizontal distance. Also, it is almost
impossible to get two counts of a section of laminae to come out the same
because of the fractured nature of the laminae. In any case, my friend
doesn't think they are varves for a number of compelling reasons.
Art
http://chadwicka.swau.edu