Peculiar structures
This
section of Chert News is a random compilation of conspicuous structures
and patterns, mainly in cherts and other silicites, worth looking at
and
marvelling about since they provide insights into
structure formation, silicification,
and fossilisation, or they concern some palaeontological detail. Also
they may pose a problem to be solved.
Own samples: Lower Devonian and Uppermost Carboniferous
/Lower Permian if not indicated otherwise.
All pictures of own samples have been taken with incident light.
Adopted from the literature: 7,
17, 23, 34.
The order of the below images is random and unrelated to the order and
numbering of the descriptions on separate pages.
Clicking on the picture leads to a more or less
detailed description of the subject, with or without explanation, on a
separate Chert News page,
( not yet
available for image Nr. 2, 4, 13, 30, 33, 36. )
A one-line explanatory description of every
picture is given at the bottom of this page.
Concise comments on the images
1: shrinkage cracks in peat, formed in an early stage of silicification
2: needle-like crystals coated with dark deposit, thus resembling
Devonian plant fragments
3: quartz crystals grown in soft degraded wood, with inclusions of wood
or debris
4: enigmatic structures in agate-like chalcedony
5: gypsum crystals stained with iron oxides, grown from dissolving
pyrite cubes in Permian chert
6: coniferous-type wood, pith rays torn asunder before silicification
7: degraded wood, shrunk and broken into blocks in an early stage of
silicification
8: Rhynia
shrunk after the surrounding water had turned into silica gel
9: coniferous-type wood with structured spots formed
in an early stage of silicification
10: Aglaophyton
epidermis pattern,
exceptionally well seen as a dainty meshwork
11: cracks, white precipitate, coated fungus hypha ("eye") arranged
incidentally, Rhynie chert
12: clots in silicified wood usually misinterpreted as mite coprolites,
Lower Permian
13: bulging shapes resembling Permian tree fern
pinnules on the surface of a
chalcedony
nodule
14: central cut face of well silicified Pachytheca
in Rhynie chert
15: tunnel-like cracks with rhombic cross-section in
wood, formed in an early stage of silicification
16: hollow calamite branch providing an illusion depending
on illumination
17: coniferous wood patterned in silicification, easily mistaken for
tree fern stem section
18: bunch of aligned nematophyte tubes in cross-section, Rhynie chert
19: Aglaophyton
epidermis pattern with stark contrast due to an
enigmatic dark deposit in every cell
20: Asteroxylon
central strand and "leaf-trace" cross-sections, bleached (by oxidation
during silicification?)
21: Trichopherophyton
central strand fragments, incidentally cut across and lengthwise
22: coniferous wood, slightly inclined sections of tracheids and pith
rays
23: Cosmochlaina
cuticle (Silurian), usually misinterpreted as an enigmatic cell
structure
24: 3-D shrinkage crack pattern in silicified peat
25: tree fern sporangia tips, uncommon hairy variety or species
26: tangle of nematophyte tubes in Rhynie chert
27: calamite
wood, tangential section with uncommonly wide pith rays in cross-section
28: Psaronius,
hollow aerial root cross-sections filled with
agates
29: cyanobacteria sheets stained with iron oxides in Permian chert
30: walnut branch pith (recent) resembling
the Artisia
pith of the palaeozoic
cordaites
31:
tiny calamite with hollow center, small wood ring, and cortex
32: shrinkage crack casts in poorly preserved
petrified wood
33: spherulite of uncommon aspect in plant tissue in Rhynie chert
34: alleged coprolites in the xylem but really fungus clots in the
phloem of a Psaronius
aerial root
35: wood tissue preserved inside quartz crystals, Kyffhäuser mountains
36: borings in limestone resembling Meandropolydora
except for loops within one another; Kimmeridge
37: fungus-induced small dots and big holes in Aglaophyton
38: part of the enigmatic persistent cortex ring usually seen on Ventarura cross-sections
39: fungus hyphae grown in water-filled cavity, coated with chalzedony and quartz topping