Observations on life; particularly spiritual

Log rafts, geology and migration

Log raft on the Macquarie River, NSW, AustraliaOne of New South Wales’ main inland rivers is being choked with woody logs and other floating debris after unprecedented flooding. Several large rafts made of wood and other debris are blocking parts of the Macquarie River in the state’s west. Logjams like these are a natural phenomena on rivers, often after flooding. Willow logs are creating many of the blockages as willows float and then bind together to form rafts bridging from one bank of the river to the other. The longest raft is about 130-metres long, with thick vegetation growing on it since it has been there for months.

Did you know that log rafts probably had a significant impact on the earth’s geology and the migration of animals across the earth?

Log raft on Spirit Lake, near Mount St Helens, Washington, USAMount St Helens

According to Wikipedia: “A log jam is a naturally occurring phenomenon characterized by a dense accumulation of tree trunks and pieces of large wood across a vast section of a river, stream, or lake. Log jams in rivers and streams often span the entirety of the water’s surface from bank to bank. Log jams form when trees floating in the water become entangled with other trees floating in the water, or become snagged on rocks, large woody debris, or other objects anchored underwater. They can build up slowly over months or years, or they can happen instantaneously when large numbers of trees are swept into the water after natural disasters. A notable example caused by a natural disaster is the log jam that occurred in Spirit Lake following a landslide triggered by the eruption of Mount St. Helens in 1980. Until they are dismantled by natural causes or humans, log jams can grow exponentially as more wood arriving from upstream becomes entangled in the mass. Log jams can persist for many decades, as is the case with the log jam in Spirit Lake.

Historically in North America, large natural “log rafts” were common across the continent prior to European settlement. The most famous natural wood raft is the Great Raft on the Red River in Louisiana, which prior to its removal in the 1830s affected between 390 and 480 km (240–300 mi) of the main channel.”

The log raft at Spirit Lake has been floating since 1980 but is gradually disappearing.

The great flood

If disasters like regional floods and volcanic eruptions can produce large log rafts, then a global flood could produce massive log rafts from floating vegetation.

Based on the estimated amount of coal in the sedimentary rocks, about 8-10 times as many plants and trees existed before the flood compared to now (Oard, 2023a).

“Post-flood log/vegetation rafts would have been wide and thick. With branches, roots, and probably leaves. These log rafts could have become floating islands of compressed and tangled plant material., which likely would have developed their own miniature ecosystems” (Oard, 2022).

Fossil trees

Vertical trees in sedimentary rocks are found in many sedimentary rocks across the world. They disprove slow sedimentation rates because these would cause the tree to decay before burial. These trees usually lack roots and soils beneath them because they probably sank vertically from log rafts during the great flood. This happened on Spirit Lake as they became waterlogged and the wider base of the trees weighed them downwards.


The swamp theory for the origin of coal has numerous problems, such as marine organisms in coal, the flat tops and bottoms of coal seams, the presence of vertical tree trunks through some coal seams, and the purity of the coal. But coal can be explained by log rafts which were buried by sediment-filled floodwater and heated by volcanic activity.

“What about multiple coal beds separated by other sedimentary rocks? Such seams can be formed from huge mats (rafts) of buoyant vegetable debris floating on the waters during the violent watery catastrophe of Noah’s flood. The vegetation, including whole forests, had been ripped up by raging flood waters. We see this on a small scale even today in local floods, which are capable of producing floating islands of vegetation and/or vegetable debris. As the bark, leaves, twigs and logs in such mats (rafts) became waterlogged, they sank to the sea floor beneath to be buried and ultimately to form coal beds. Other sediments were then washed in by the waters beneath the floating mats to cover these beds of vegetation. Further vegetable material in the mats continued to become waterlogged and to sink, and a depositional cycle of events was established. This explanation can easily account for multiple coal beds stacked between other sediments, both fossiliferous and non-fossiliferous” (Snelling, 1986).

Cyclical rising and falling of water level during the flood would quickly deposit huge amounts of sediment that contained multiple layers of plant debris that had been log rafts (Oard, 2023b).

Even in judgment God was being merciful to humanity because the coal formed during the flood is an excellent form of energy.

Animal migration

After the flood, God told Noah and the animals to spread across the earth (Appendix) and He provided a means for this to happen. The way they reached remote continents like America and Australia was probably via land bridges and log rafts.
Migration from the Middle East via land bridges and log rafts
After the great flood, animals migrated across the earth to recolonize the planet. They would have been assisted by land bridges (for example, across the Bering Straight) during the ice age that followed the flood (Oard, 2020). So the ice age after the flood enabled the migration of animals and people across the earth. This ice age was a consequence of the flood and volcanism.

It is also recognized that plants and small animals can cross large stretches of water on natural rafts. Many tropical ocean currents have a speed of at least two knots; this would amount to 80 km [50 miles] a day, and 1600 km [1000 miles] in three weeks. Some log rafts would have been floating at the end of the flood. These would have been huge. This may have been how plants and small animals travelled to places that were not connected via a land bridge. For example, from Asia to Australia.

Secular research

It is interesting that secular researchers have recently used to idea of vegetation rafts to explain some biogeographical puzzles (Cox, 2023). In this case they stated that some African monkeys must have travelled across the Atlantic ocean on rafts of vegetation. They were influenced by a video showing upright trees on vegetation rafts floating down the Chagres river (Panama Canal) after heavy rain in December 2010.


The flood was God’s judgment of the rebellion and wickedness of mankind. Those judged perished in the flood. Those rescued were enabled to repopulate the earth via land bridges and log rafts.

God is merciful to those who trust Him. He protected Noah’s family and the animals on the ark. And he provided land bridges and log rafts to help them migrate across the earth.

God saved eight people from the global flood. Today, He is saving millions of people through His Son Jesus. Like the ark, Jesus is the means of salvation (Jn. 10:9).

In future God will protect His people from the coming judgement on earth. And those living at that time will repopulate the earth during the millennial reign of Christ.


Log rafts probably had a significant impact on the earth’s geology and the migration of animals across the earth. But these were massive rafts that occurred during Noah’s global flood, which greatly exceeded the size and prevalence of log rafts today.

Appendix: God’s command to spread across the earth

After the flood, God said that the animals were to spread across the continents of the earth (Gen. 8:17):
– “swarm on the earth, and be fruitful and multiply on the earth” (ESV).
– be fruitful and multiply throughout the earth (NIV).
– “increase and be fruitful and multiply on the earth!” (NET).
– “spread over the earth and be fruitful and multiply on the earth” (NLT).
According to the NET, the Hebrew text says, “and let them swarm in the earth and be fruitful and multiply on the earth”.

The animals obeyed this command. In 1859 European wild rabbits were introduced into Australia so they could be hunted for sport. Within 50 years rabbits had spread across almost the entire continent.

This command is similar to God’s instruction to Noah and his family:
–  “Be fruitful and increase in number and fill the earth” (Gen. 9:1NIV).
– “be fruitful and increase in number; multiply on the earth and increase upon it” (Gen. 9:7).
He wanted them to “Be scattered over the face of the whole earth” (Gen. 11:4, 9).

But the people didn’t obey this command until they were forced to because of the emergence of difference language groups (Gen. 11:1-9). Instead they settled in Mesopotamia where they built a city.

Cox G, 2023, “Transatlantic rafting monkeys”, Creation, 45(2), 14-17.
Oard M, 2020, “Land bridges after the flood”, J of Creation 34(3), 109-117.
Oard M, 2022, “When and how did the marsupials migrate to Australia?”, J of Creation 36(2), 90-96.
Oard M, 2023a, “Log mats solve many geological riddles”. Creation, 45(1), 40-43.
Oard M, 2023b, “A BEDS origin for coal”. Creation, 45(2), 42-53.
Snelling A, 1986, “Coal beds and Noah’s flood part 2”, Creation, 9(1), 16.
Written, March 2023

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