In 1992 together with his geologist wife Edith, also now deceased, he published a work describing two cometary collisions in the 11th and 8th millennia BC. This is available online in German with the Introduction in English(d). Frank Dörnenburg has written a highly critical review (in German) of this book, concluding with the comments – Alles in allem habe ich mit ein wenig Internetsuche und Schulstoff die Basisbeweise des Buches aushebeln können, und diese nicht auf Fehler sondern unzweideutige Manipulationen der Autoren zurückführen können. “All in all I have with a little Internet search and schoolwork can nullify the basic proofs of the book, and this can not be reduced to unambiguous error but manipulation of the authors. Ich kann Autoren die bei so etwas derart dreist zu Werke gehen nicht trauen, und jeden Beleg nachzuprüfen ob sie wenigstens da die Wahrheit gesagt haben, dafür ist mir meine Zeit zu schade. I can authors with something so brazenly works will not be trusted, and verify each document if they have at least as telling the truth, but my time is too precious.” (Google translator)
With a mass of technical data they also claim that there was an earlier impact around 11,000 BC when a comet struck the northern hemisphere in fragments.
Wikipedia offers an interesting critical review(b) of the Tollmanns’ theory, while the Golden Age Project established by Christian O’Brien presents a more sympathetic assessment(c).
These Late-Glacial impacts are suggested as the cause of the ‘Debacle’ flood in Ontario and the ‘Spokane Flood’ in the Columbia Basin. The Tollmans then claim that a second cometary impact occurred in 7552 BC that broke into seven pieces, one of which fell in the Atlantic. They maintain that the consequences of this event were the Flood of Noah and the Holocene Extinctions.
The Tollmanns backed up their claim with the results from field studies around the Köfels crater in the Austrian Tyrol. In 2008 two British researchers, Alan Bond & Mark Hempsell, controversially proposed that the Köfels impact was caused by an asteroid that was recorded on an Assyrian cuneiform tablet, which itself is a copy of an earlier Sumerian document dated to 3123 BC. It is also suggested that the same event was responsible for the destruction of Sodom and Gomorrah.
Towards the end of his life Tollman appears to have become somewhat irrational, for example, on the basis of the prophecies of Nostradamus as well as a local ‘prophet’, Alois Irlmaier, together with the solar eclipse of August 11, 1999,and other signs, he predicted a global catastrophe for August 1999 and retreated to a bunkered existence, fearing the impending destruction(f).
Over ten years later other scientists claimed that a field of craters around Lake Chiemsee, in southeast Bavaria, was caused by fragments from a huge comet or asteroid that broke up in the atmosphere(a).*The Wikipedia entry for the ‘Chiemgau impact hypothesis’ dismisses the hypothesis as an “obsolete scientific theory”. However, others beg to differ(g)(h).*
It should be noted that Lake Chiemsee is just north of the Austrian border and only about 50 km from the Köfels crater. Artefacts, including coins, seem to have been strongly heated on one side. This fact, together with Roman reports of stones falling from the skies and dendrochronology has suggested a date of around 200 BC for the event.
(f) http://www.beobachter.ch/justiz-behoerde/buerger-verwaltung/artikel/alexander-tollmann-die-endzeitangst-ist-begruendet/ (offline May 2017 – see Archive 2968) mixed German & English
Mike Baillie is Emeritus Professor of Palaeoecology in the School of Archaeology and Palaeoecology, Queen’s University, Belfast. He is a dendrochronologist of world renown, who outlined in his recent book  the evidence for catastrophic encounters with asteroids or comets over the past five millennia that opened a whole new chapter in the search for the truth about our past. Baillie ascribes these events to 2354-2345 BC, 1628-1623 BC, 1159-1141 BC, 208-204 BC and 536-545 AD. He touches on a number of legendary and historical events such as the Deluge, the Exodus and King Arthur, but seems to studiously avoid any direct reference to Atlantis. Nevertheless, his theory in conjunction with the suggestions of writers such as Emilio Spedicato enhances the possibility of the destruction of Atlantis being a consequence of a more widespread catastrophe.
In 2004 it was revealed that a very large comet or asteroid, estimated to be ¾ of a mile in diameter, crashed into what is now Germany. The date is calculated at 200 BC, which coincides with one of Baillie’s dated catastrophes. A crater field stretching from the town of Altoetting to Lake Chiemsee is all that remains today.
Perhaps even more relevant to our study was a PowerPoint presentation(b) from Baillie to a Quantavolution Conference in Athens in 2011, which offered compelling evidence for a catastrophic event in 2345 BC. His data reinforces the work of George Dodwell who demonstrated with his study of ancient gnomons, decades earlier, that something dramatic happened to the rotational axis of the Earth in 2345 BC, which is possibly the same 2346 BC encounter with a comet proposed by William Whiston in 1696. At the same conference Baillie also presented evidence for dating the eruption of Thera to 1628 BC.
Baillie is also co-author with Patrick McCafferty of a fascinating work that reinterprets some of the heroes and gods of Celtic mythology as a coded account of our ancestors’ observation of a close encounter or impact of comets with the Earth. However, Baillie’s books should be read in conjunction with an equally compelling volume(a) by David Talbot and Wallace Thornhill who offer a complementary but rather than conflicting interpretation of early man’s perception of highly visible cosmic events. Talbot and Thornhill have linked ancient myths and thousands of petroglyphs with their view of an electric universe, where large-scale plasma phenomena were witnessed and recorded by preliterate man. Their book has drawn extensively on the work of Dr. Anthony Peratt, who has gathered and classified an enormous database of petroglyphs from all over the world that are apparently a record of celestial demonstration(s) of plasma physics.
(c) http://www.cais-soas.com/CAIS/Religions/non-iranian/Judaism/Persian_Judaism/book6/pt1.htm (half way down page)