I wanted to find out more information in regards to isostatic adjustment, namely information pertaining its effect on the outer periphery (boundary) of the Northern Tectonic Plates, because it seemed to me that nothing was being said about this region most of which lay beneath the oceans. This is important because as we are now aware, our present day IceAge consists of cyclical interglacial (every 20,000–25,000 years)and glacial (every 75,000-80,000 years) periods, and that these need to have undergone very specific events to enable the cyclical switch back and forth.
I hold to the theory that the shift bringing us into a new glacial period/cycle from our present interglacial period, would include a warming ocean and earth. A warming ocean would generate greater evaporation and in turn denser salt (in oceans) left behind that then sinks and because this “sinking salt” is what generates our conveyor belt currents, that in turn create wind, it then stands to reason that stronger and more frequent hurricanes would extend over the year, and this in turn would mean more moisture being pushed into the upper atmosphere that then falls as “big” snow in the North and South hemisphere that rebuilds the glaciers.
And so as to kick starting the next glacial period this brings us to a very important question — what is the natural occurrence that heats the ocean?! My theoretical answer— friction.
As isostatic adjustment causes land to rebound and sink in various areas of affected tectonic plates, this action extends to the entire plate and to its most outer reaches (the edges) that during the last glacial maximum, had lost some of its curvature (flattening out slightly). This flattening out caused the plate edges to do various things that affected the edges of adjacent Tectonic Plates. At various places along these edges there was enhanced events, such as greater subduction, and in other instances where plates had butted against one another or were slightly apart, massive collisions would have occurred, that formed mountains, and in incidences there was slipping along adjacent plate edges, this would become more enhanced. It’s this “slipping” that has the greatest potential for generating friction that in turn heats the ocean and atmosphere.
Now with the above realized, the question then becomes, what is causing oceans to heat up excessively today?
My theoretical answer— as the lands in the north rebound during the last portion of the interglacial period, it does so exponentially, and the equal and opposite reaction to this is that the edges of the northern plates affected are now being drawn up from their “flattened out” shape and reverting back to their more natural curvature … also in exponential fashion, and as such, more friction is being generated. For some reason, the experts are not paying attention … or given far little attention to this natural phenomenon, butt the focus is on human causes ie: our use of fossil fuels and wastes are causing the planet … earth and oceans to heat and so changing our weather patterns. This is only a half-truth. We do have an effect, butt it enhances the natural cycle that is also occurring. If we want to protect coastal regions … where approximately 3 billion people live, then we need to hope that the next glacial period kicks in to the degree that the exponential rebound either slows significantly, stops or reverses, and the only way this can happen is with a rapid rebuilding of the glaciers in the north.
First I googled: diagrams that show what occurred to the tectonic plates in the Northern hemisphere as glaiciars grew during the last glacial period, and received the following AI Overview info:
During the last glacial period, the massive weight of ice sheets caused the Earth's crust to undergo glacial isostatic adjustment (GIA). The landmasses in the Northern Hemisphere were pushed downward, while areas at the periphery of the ice sheets bulged upward. This process involves the flexible lithosphere and the viscous mantle, and is not a permanent tectonic plate shift, but rather a temporary deformation and subsequent rebound.
I then googled: were the outer edges of the tectonic plates in the northern hemisphere affected by the last glacial maximum, and received AI Overview info:
Yes, the outer edges of the tectonic plates in the Northern Hemisphere were significantly affected bythe Last Glacial Maximum (LGM). The primary mechanism for this effect was glacial isostatic adjustment (GIA), involving the depression of the crust by ice sheets and the subsequent migration of mantle material, which also affected adjacent areas, including plate boundaries
- Crustal Deformation: The immense weight of massive ice sheets (up to 3-4 km thick) depressed the Earth's crust in glaciated regions (e.g., Northern North America and Northern Europe). This displacement caused the adjacent, non-glaciated crust at the periphery of the ice sheets (the "forebulge" regions) to bulge upward. These effects extended over thousands of kilometers, influencing areas near plate boundaries.
- Sea Level Changes: Global sea levels dropped by approximately 120-125 meters during the LGM as water was locked in ice sheets. This drop exposed large areas of the continental shelves as dry land, including regions at the edges of continents near plate boundaries (e.g., the Bering Land Bridge and the North Sea plain). After the ice melted, the collapse of the peripheral forebulge and global sea-level rise caused marine incursions into previously dry land areas.
- Seismicity and Stress Changes: The loading and unloading of the Earth's crust caused significant changes in stress and strain, which in turn affected earthquake activity (seismicity). During the LGM, the weight of the ice generally suppressed fault movement beneath the ice. During deglaciation, however, the rapid removal of this weight and the subsequent crustal rebound and forebulge collapse induced stress changes that triggered earthquakes in both formerly glaciated and adjacent regions, some of which are near plate boundaries. This post-glacial seismicity continues in some areas today, such as parts of Scandinavia and North America.
- Mantle Flow: The depression and rebound of the crust required the flow of viscous mantle material away from the glaciated areas (during glaciation) and back towards them (during deglaciation). This mantle flow influenced the lithosphere over a broad scale, impacting the stress field near plate boundaries.
No comments:
Post a Comment