Tollmann's bolide hypothesis is a hypothesis presented by Austrian paleontologist Edith Kristan-Tollmann and geologist Alexander Tollmann in 1994. The hypothesis postulates that one or several bolides (asteroids or comets) struck the Earth around 7640 ± 200 years BCE, with a much smaller one approximately 3150 ± 200 BCE. The hypothesis tries to explain early Holocene extinctions and possibly legends of the Universal Deluge.
The claimed evidence for the event includes stratigraphic studies of tektites, dendrochronology, and ice cores (from Camp Century, Greenland) containing hydrochloric acid and sulfuric acid (indicating an energetic ocean strike) as well as nitric acids (caused by extreme heating of air).
Christopher Knight and Robert Lomas in their book, Uriel's Machine, argue that the 7640 BCE evidence is consistent with the dates of formation of a number of extant salt flats and lakes in dry areas of North America and Asia. They argue that these lakes are the result remains of multiple-kilometer-high waves that penetrated deeply into continents as the result of oceanic strikes that they proposed occurred. Research by Quaternary geologists, palynologists and others has been unable to confirm the validity of the hypothesis and proposes more frequently occurring geological processes for some of the data used for the hypothesis. Dating of ice cores and Australasian tektites has shown long time span differences between the proposed impact times and the impact ejecta products.
Scientific evaluation
Quaternary geologists, paleoclimatologists, and planetary geologists specializing in meteorite and comet impacts have rejected Tollmann's bolide hypothesis. They reject this hypothesis because:
- The evidence offered to support the hypothesis can more readily be explained by more mundane and less dramatic geologic processes
- Many of the events alleged to be associated with this impact occurred at the wrong time (i.e., many of the events occurred hundreds to thousands of years before or after the hypothesized impacts); and
- There is a lack of any credible physical evidence for the cataclysmic environmental devastation and characteristic deposits that kilometer-high tsunamis would have created had they actually occurred.
Global sea level curve for the Late Pleistocene and Holocene
Evidence used by proponents of the Tollmann's bolide hypothesis to argue for catastrophic Holocene
extinctions have alternative explanations by more frequently occurring
geological processes. The chemical composition and presence of volcanic ash with the specific acidity spikes in the Greenland ice cores shows evidence that they result from volcanic instead of impact origins. Also, the largest acidity spikes found in Antarctica ice cores have been dated to 17,300 to 17,500 BP, which is significantly older than hypothetical Holocene impacts. The formation of modern salt lakes and salt flats is explained by the concentration of salts and other evaporite minerals by the evaporation of water from stream-fed lakes lacking external outlets, called endorheic lakes,
which commonly occur in arid climates on both hemispheres on Earth. The
composition of the salts and other evaporite minerals found in these
lakes is consistent with their precipitation from dissolved material
continually carried into the lakes by rivers and streams and subsequent
concentration by evaporation, instead of evaporation of sea water.
Whether a lake becomes salty or not depends on whether the lake lacks
an outlet and the relative balance between the inflow and outflow of
lake waters via evaporation.
Ocean water accessing a continental lake as the result of a single
catastrophic event, as Tollmann's hypothesis proposes, would contain an
inadequate amount of dissolved minerals to produce, when evaporated, the
vast quantities of salts and other evaporites found in the salt lakes,
flats, and pans cited as evidence of a mega-tsunami by this hypothesis.
Geological criticism
Isostatic rebound
Isostatic rebound in the British Isles
Many published papers demonstrate that isostatic depression of the Earth's
crust happened in the early Holocene. This process has led to
submerging substantial portions of coastal areas adjacent to continental
ice sheets and resulted in the accumulations of marine sediments and fossils within them. A well-documented example of flooding caused by isostatic depression is the case of Charlotte, The Vermont Whale, a fossil whale found in the deposits of the former Champlain Sea.
Like many similar marine deposits, the sediments, which accumulated
within the Champlain Sea lack the physical characteristics; i.e.
sedimentary structures, interlayering, and textures, that characterize
sediments deposited by a mega-tsunami.
These deposits and the associated fossils have been dated to
significantly earlier periods than the times the bolide hypothesis
proposed. In case of the Champlain Sea, its sediments started to
accumulate around 13,000 BP, almost 3,400 years before the oldest of the
hypothesized Holocene bolide impacts.
Dating
Lake Bonneville and other ice age pluvial lakes (17,500 years BP), and modern remnants
A significant amount of the physical evidence used by Kristan-Tollmann and Tollmann,
as supporting their hypothesis, is either too old or too young to have
been created by this hypothesized impact. In many cases, it is hundreds
to thousands, and in one case hundreds of thousands, of years too old to
be credible evidence of a Holocene impact. The research that dates the tektites, which Tollmann's bolide hypothesis regards as indicative for the timing of the impact, is outdated. Later research, has dated the Australasian tektites to the Middle Pleistocene; about 790,000 years BP.
In addition, the formation of salt lakes and salt flats is neither
synchronous nor consistent with the hypothesized impacts having occurred
about either 9,640 BP or 5,150 BP. For example, in case of Lake Bonneville, Lake Lahontan, Mono Lake, and other Pleistocene pluvial lakes
in the western United States, the transition to salt lakes and salt
flats occurred at different times between 12,000 and 16,000 BP.
Thus, the change from freshwater to salty water and eventually salt
flats started over 2,400 to 6,400 years before the oldest of the impacts
hypothesized by the Tollmann bolide hypothesis occurred. As a result,
it is impossible that the formation of these salt lakes could have been
associated with the impact hypothesized by Kristan-Tollmann and
Tollmann.
Megatsunami
The megatsunami-producing Storegga Slide in Norway has been dated to approximately 6225–6170 BCE
There exists a lack of credible physical evidence of either multiple-kilometer-high tsunami
waves penetrating deeply into continents, and the ecological
devastation these would have caused. Thousands of paleoenvironmental
records constructed from the study of lakes, bogs, mires, and river
valleys all over the world by palynologists have not shown the existence of such a megatsunami. In the case of North America, research published by various authors,
provide detailed records of paleoenvironmental changes that have
occurred throughout the last 10,000 to 15,000 years as reconstructed
from pollen and other paleoenvironmental data from over a thousand sites throughout North America. These records do not recognize indications of either a resulting catastrophic environmental devastation or layers of tsunami deposits, which the mega-tsunamis postulated by Tollmann's bolide hypothesis would have created. Paleovegetation maps
illustrate a distinct lack of the dramatic changes in North American
paleovegetation during the Holocene, which would be expected from the
cataclysmic ecological and physical destruction that a continental-wide
mega-tsunamis would have certainly have caused.
Grimm et al. in a paper published in Science in 1993, documented a 50,000-year-long record of environmental change by the analysis of pollen from an 18.5 m (61 ft) core from Lake Tulane in Highland county, Florida.
Because of the low-lying nature of the peninsula, in which this part of
Florida lies, this lake and the area around it would have been flooded
and covered by tsunami deposits along with many of the other lakes and
bogs described in their, and other publications.
The forests and associated ecosystems of these areas would have been
flooded and completely destroyed by the mega-tsunamis proposed by
Kristan-Tollmann and Tollmann.
Despite its location, both the core and the pollen record recovered
from Lake Tulane lacks any indication of an abrupt, catastrophic
environmental disruption,
which the mega-tsunamis proposed by Tollmann's bolide hypothesis would
have caused. Sedimentary cores obtained from Florida and other locations
also lack sedimentary layers that have the characteristics of sediments
deposited by either tsunamis or mega-tsunamis.
The cataclysmic scale of physical and ecological destruction that
a megatsunami, like the one proposed by Kristan-Tollmann and Tollmann,
would have caused, has not been recognized within the majority of
long-term environmental records. Over a thousand cores from North
America for which Holocene paleoclimatic and paleoenvironmental records
have been reconstructed do not show evidence for the drastic
environmental changes resulting from a large Holocene impact. There is a
similar lack of evidence for mega-tsunami related, Holocene,
catastrophic environmental disruptions and deposits reported from
environmental records reconstructed from thousands of locations from all
over the world. Other megatsunamis have been shown in coastal sediments
analyzed by geologists and palynologists and point to tsunamis locally
caused by either earthquakes, volcanic eruptions,
or submarine slides. These non-impact related tsunamis show abundant
records of their environmental effects through the study of pollen from
cores and exposures.
Members of the Holocene Impact Working Group
have published papers advocating the occurrence of mega-tsunamis
created by extraterrestrial impacts at various times during the Holocene
and Late Pleistocene. However, none of these proposed impacts match either the cataclysmic scale or timing proposed by Kristan-Tollmann and Tollmann for their hypothesized bolide.
