18 March 2006

Flooding the zone of human culture

Flood Myths! Well, now I get to offend *lots* of people, don't I? Every damn culture seems to have its own variation on the theme of flooding, and I do mean just about every single one. That said exactly what happens differs and also the survival mechanisms. For some cultures this is just rising waters over lowlands washing over them and others it is the rain with submergence of everything. And as the 'why' of it varies so do the survival mechanisms vary, from the Biblical great Ark to, well, something along the lines of : 'Our people saw the waters rising and walked to high ground. The idiots on the seashore wanted to stay and be saved by someone.'

Now some of these myths are purely localized, like the Black Sea fisherman picking up remnants of the Samothracian culture that used to live on dry land, until the Mediterranean broke through the retaining rock and flooded it. *That* was a pretty fast flood and submersibles today can still see the outlines of villages and such down there. The Utnapishtim and related predecessors and descendent stories do tell of a great flood, somewhat localized, that may have been a large storm hitting during a high tide that actually is recorded in sediment layers.

A fascinating suite of stories amongst the tribes in the northwestern US and southwestern Canada tell of a sudden deluge that swept all before it. And a few tell of its repeating a couple of times and warn forevermore that it can return. Like the Utnapishtim story this may be the recording of actual events. Of most interest is the Scablands of Washington State in the US. Trying to piece together the remains of the Spokane Floods (later Missoula Floods) and Lake Missoula in Montana finally fell into place as the timing was put together to coincide with the retreat of the Continental Glaciers some 13-15,000 years ago. Now glacial retreat is an average sort of thing over time, and one will expect to see some thrusting forward in some areas as we can see in modern day Alaska. Overall the glaciers retreat, but flow rates of the ice varies locally and some parts will flow faster and thrust forward and melt repeatedly until their source is diminished. Lake Missoula was one such area where a glacial dam was formed and meltwater backed up into the space behind it, forming lake Missoula. Water pressure will cause seepage under the glacial ice, until the ice lifts, breaks from the sheer strain and gives way, releasing the entire contents of the lake.

One of the fun features of the Scablands, unless you are walking across them, is the boulder dunes at the bottom. That was a horrifically puzzling thing in the late 19th and early 20th centuries as no wind could make dunes like that and not deposit sand and other things. It was only by getting up to the plateau, looking around, seeing a mark along all the cliffs and looking down that the pieces fell into place. These were not dunes... they were ripple marks! From there you can start doing entrainment and speed analysis, look at flow height and see that the reason for the lack of smaller material is that it could not settle. These were the smallest particles that could only be saltated along the bottom of the channel. Fist sized rocks and upwards, everything else gets entrained and taken out to sea. This happened about 40 times or so... well would you not speak ill of the Great Thunderbird and the Waters it has at its command!

The maritime Canadian tribes on the other side of the continent had obvious interaction with the Norse to get their Ice Giant magicians. The archeological evidence in the eastern part of North America is somewhat more spotty, but when a common theme developed in another culture shows up in an area of known interaction between that culture the indigenous, then you can only see the resultant as either a transplantation or mixture between cultures. Similarly the Russian influence with some Inuit tribes and others sees the ahistorical Noah in one or two tribes, where the surrounding tribes talk more consistently about ravens, canoes, beavers, otters and the Thunderbird.

Now, back to the Thunderbird, because that beastie has another set of floods associated with it, namely the coastal floods of the northwestern coast of north america, stretching from Oregon to Alaska. The late 20th century unearthing of the last flood detritus layer and evidence of sheered of trees along the coast, points to a tsunami event. This event was also recorded in northern Japan and written down. Digging down further and a regular series of these events are recorded until you are in waterlogged muck and start getting to more solid rock. These events are the Cascadia fault letting go and the resultant tsunami after a long undersea magnitude 9 earthquake. The Thunderbird doth fly for five minutes or so, its wings beating on the ground and the seas rising up in great floods to wash the coast. Warning: do not mock the Thunderbird! It is still there and the fault has gone beyond its earthquake periodicities of 100-200 years with the last quake in 1700 and recorded tsunami in Japan. The subduction of the Juan de Fuca plate is the cause of this, and the Cascade range volcanoes.

More central tribes in the northeast US and Canada may have evidence of Lake Tonawanda as it grew from glacial melt water. Having grown up in that area, let me say that the uniform red clay is very hard to dig through, somewhat porous to water and the topsoil subsides somewhat. Basement flooding is common with very rainy seasons of the remnants of hurricanes that can struggle to get there. The ground is compacting and sinking, but not going anywhere laterally, like the delta in Louisiana. And other stories in the south and western US indicate that Lake Bonneville is also remembered. One thing to remember is that is peoples move, they take and adapt stories from their previous range into their new range, melding stories together and transforming them.

And for everyone on the planet, just about every culture would have been exposed to the fact that the thinner edges of the continental plates were exposed during the last glacial period. These are the continental shelf regions. With mean sea level down a few hundred feet, vast areas of land were exposed for thousands of years and entire ecosystems took hold on them. And as the climate started to get warmer and wetter, glacial retreat started to add water back into the ocean basins, thus rising the water levels. To those on the coasts the actual upper continental areas would, indeed, look like mountains in the distance. And to those who traded with people closer to it, they would know that it was just cooler and drier high ground. Indeed, there was a global flood. It did not last for a mere 40 days and nights. It started about 15,000 years ago, or so, and continues to this very day.

No comments: