was demonstrated in research on paleosols. Holmqvist and Schlyter (2000) examined the chronosequence of closely superimposed paleosols from an arctic/alpine
meadow soil in northern Sweden with radiocarbon
(14
C) dating of asexual spores of
vesicular-arbuscular mycorrhizae, and determined the long-term (i.e., over a millennium time span) loss rate of organic carbon. Hormes et al. (2004) used
14 C dating to
estimate that C. geophilum “spores” found from buried soils in glacial sediments in
northern Sweden were 5000–6000 years. BP, and this information was used to
clarify the geochronology of glacier fluctuations in the region. (Note, however,
that the “spores” were actually sclerotia; C. geophilum does not produce spores
[LoBuglio 1999]). Kobayashi et al. (2015) studied the Late Holocene peaty sediment
in Rishiri Island, Hokkaido, Japan and found the distribution of Cg sclerotia grains
from the bottom to top of the sediment having the highest density in the sediment of
ca. 3 ka. They suggested that the fluctuation of density of Cg grains indicates the past
environmental change of dry-wet condition, i.e., the favorable condition for the
possible host plant, Pinus pumila.
A case of C.geophilum sclerotia contribution in recent earth science appears in the
discussion of the trigger of Younger Dryas event. The Younger Dryas is named for
the climate change that abruptly occurred in the Northern Hemisphere about
14,500 years ago until 11,500 years ago, bringing back near-glacial conditions in
the period when Earth’s climate began to shift from a cold glacial world to a warmer
interglacial state. Other proxy records, including varved lake sediments in Europe,
also display these abrupt shifts. The Younger Dryas is clearly observable in
paleoclimate records from many parts of the world (https://www.ncdc.noaa.gov/
abrupt-climate-change/The%20Younger%20Dryas). Regarding the cause of the
event, one theory suggests: During the transition from the last glacial period into
the present interglacial, the North American ice sheet (Laurentide Ice Sheet) was
rapidly melting and adding freshwater to the ocean. Geochemical evidence from
ocean sediment cores supports this idea. A more northerly routing of meltwater has a
greater impact on the salinity and density of the surface ocean in the North Atlantic,
which can cause a slowing of the ocean’s thermohaline circulation and climate
changes around the world. As the meltwater flux abated, became less intensive,
the thermohaline circulation strengthened again and climate recovered (https://www.
ncdc.noaa.gov/abrupt-climate-change/The%20Younger%20Dryas).
While, another theory suggests: A cometary or meteoritic body or bodies hit
and/or exploded over North America 12,900 years ago, causing the Younger Dryas
climate episode. Cosmic impact objects such as magnetic spherule, carbon spherule,
nanodiamond particle, soot material, and some more were found from the YD
stratigraphy sediments and ice cores (Firestone et al. 2007; Kinzie et al. 2014;
Wolbach et al. 2018a, b). Counter evidences against extraterrestrial theory were
provided to prove that the YD event was triggered by terrestrial impact and not by
cosmic impact, in terms of precise examination of the C. geophilum sclerotia grains
collected from the YD stratigraphy (Scott et al. 2010; Pinter et al. 2011). Daulton
et al. (2016) determined the so-called “nanodiamond” as graphene in Cg sclerotia
grains. The grains of C.geophilum sclerotia, archiving natural history have become
to play a key role in the discussions.
1 Introduction
9
meadow soil in northern Sweden with radiocarbon
(14
C) dating of asexual spores of
vesicular-arbuscular mycorrhizae, and determined the long-term (i.e., over a millennium time span) loss rate of organic carbon. Hormes et al. (2004) used
14 C dating to
estimate that C. geophilum “spores” found from buried soils in glacial sediments in
northern Sweden were 5000–6000 years. BP, and this information was used to
clarify the geochronology of glacier fluctuations in the region. (Note, however,
that the “spores” were actually sclerotia; C. geophilum does not produce spores
[LoBuglio 1999]). Kobayashi et al. (2015) studied the Late Holocene peaty sediment
in Rishiri Island, Hokkaido, Japan and found the distribution of Cg sclerotia grains
from the bottom to top of the sediment having the highest density in the sediment of
ca. 3 ka. They suggested that the fluctuation of density of Cg grains indicates the past
environmental change of dry-wet condition, i.e., the favorable condition for the
possible host plant, Pinus pumila.
A case of C.geophilum sclerotia contribution in recent earth science appears in the
discussion of the trigger of Younger Dryas event. The Younger Dryas is named for
the climate change that abruptly occurred in the Northern Hemisphere about
14,500 years ago until 11,500 years ago, bringing back near-glacial conditions in
the period when Earth’s climate began to shift from a cold glacial world to a warmer
interglacial state. Other proxy records, including varved lake sediments in Europe,
also display these abrupt shifts. The Younger Dryas is clearly observable in
paleoclimate records from many parts of the world (https://www.ncdc.noaa.gov/
abrupt-climate-change/The%20Younger%20Dryas). Regarding the cause of the
event, one theory suggests: During the transition from the last glacial period into
the present interglacial, the North American ice sheet (Laurentide Ice Sheet) was
rapidly melting and adding freshwater to the ocean. Geochemical evidence from
ocean sediment cores supports this idea. A more northerly routing of meltwater has a
greater impact on the salinity and density of the surface ocean in the North Atlantic,
which can cause a slowing of the ocean’s thermohaline circulation and climate
changes around the world. As the meltwater flux abated, became less intensive,
the thermohaline circulation strengthened again and climate recovered (https://www.
ncdc.noaa.gov/abrupt-climate-change/The%20Younger%20Dryas).
While, another theory suggests: A cometary or meteoritic body or bodies hit
and/or exploded over North America 12,900 years ago, causing the Younger Dryas
climate episode. Cosmic impact objects such as magnetic spherule, carbon spherule,
nanodiamond particle, soot material, and some more were found from the YD
stratigraphy sediments and ice cores (Firestone et al. 2007; Kinzie et al. 2014;
Wolbach et al. 2018a, b). Counter evidences against extraterrestrial theory were
provided to prove that the YD event was triggered by terrestrial impact and not by
cosmic impact, in terms of precise examination of the C. geophilum sclerotia grains
collected from the YD stratigraphy (Scott et al. 2010; Pinter et al. 2011). Daulton
et al. (2016) determined the so-called “nanodiamond” as graphene in Cg sclerotia
grains. The grains of C.geophilum sclerotia, archiving natural history have become
to play a key role in the discussions.
1 Introduction
9