Page 6 - Petrology of Sedimentary Rocks

PREFACE

This syllabus is by no means intended as a textbook on sediments. Rather, it was
originally intended to supplement lecture and laboratory material given in sedimentary
petrology courses at The University of Texas. Consequently it is to be used in
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conjunction with standard textbooks in the field such as Pettijohn, Sedimentary Rocks,
Krumbein and Pettijohn, Manual of Sedimentary Petrology, Blatt, Middleton and
Murray, Origin of Sedimentary Rocks, Pettijohn, Potter and Siever, Sand and Sand-
stones, Bathurst, Carbonate Rocks, Carver, Procedure in Sedimentary Petrology, or
Royse, Sediment Analysis, for this reason no references to the literature are given, as
these references are readily available in those texts. Persons responsible for particular
ideas are indicated by parentheses. Figure revisions are by Connie Warren.

None of the statements herein are to be regarded as final; many ideas held valid
as recently as two years ago are now known to be false. Such is the penalty of
research. This syllabus merely states the present condition of the subject. The rapid
rate at which sedimentary petrologic data is now accumulating is bound to change
radically many of the ideas contained within.

Much of this syllabus is based on material obtained in sedimentation courses
taught at the Pennsylvania State College by Paul D. Krynine and J. C. Griffiths, l945-
1950, together with later modifications of and additions to this material by the present
author during his own work on sediments after 1950. I would therefore like to dedicate
this booklet to those two inspiring teachers: Krynine, without peer as a sedimentary
petrographer, mineralogist and man of ideas (see JSP Dec. 1966); and Griffiths, pioneer
in the application of rigid statistical techniques to description of the physical properties
of sediments.

Historically, Henry Clifton Sorby of Sheffield, England (1826-1908) is the founder
of sedimentary petrography (and microscopic petrography in general). His work was so
voluminous and so excellent that it was not matched until well into the twentieth
century, fifty years after his publications. Although the microscope had been used
earlier to study slides of fossils and a few rocks, Sorby was the first geologist to realize
their importance, cut his first thin section in 1849 (a cherty limestone) and published on
it in 1851, the first paper in petrography. Sorby demonstrated his technique to Zirkel in
I86 I, and thus igneous petrography was born. Sorby’s three monumental papers were on
the origin and temperature of formation of crystals as shown by their inclusions, etc.
(1858); on the structure and origin of limestones and petrography of fossil invertebrates
(1879); and on quartz types, abrasion, surface features, and petrography of schists and
slates ( 1880). He made 20,000 paleocurrent measurements for a decade before his
publication (1859). He also has fundamental publications in structural petrology (18561,
studied fluvial hydraulics, founded the science of metallography in 1864, and devoted
the latter part of his life to study of recent sediments and marine biology. A good
biography is given by Judd (I 908, Geol. Mag.), and Naturalist (I 906) lists some 250 of
Sorby’s papers; a short review of Sorby’s career is given in J. Geol. Educ. 1965. Even
today his papers deserve detailed study by every petrographer. Two volumes of his
collected works have been edited by C.H. Summerson (publ. by University of Miami).

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