Geology

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    1790's James Hutton recognized that land continually being eroded into rivers and sea. But where was new land coming from? If it were just precipitating out and gradually filling the oceans, it would appear in layers. But the fact that it appeared heated and tilted or buckled, meant due to action of Earth's internal heat and volcanic action. The proof was the granite veins which intruded through sedimentary rock layers. Hutton's ideas of a continually regenerating geology directly contradicted the current view of a recently created, decaying world.

    At Siccar Point he found geology which confirmed his ideas. Vertical layers of gray sandstone jutted upwards, overlaid by layers of tilted red sandstone, and in between lay gray rubble that looked just like a modern beach. The only way to account for these strata was if there had been several cycles of deposition, erosion, submerging and uplift.

    If Roman ruins were still standing 2000 years later, how could you fit the geology of places like Siccar Point into a time frame of 4000 years?

    1815 surveyor and canal builder William Smith published the first regional geological map. He carefully documented a consistent, well-ordered succession of rock types across England that could not be the result of a single chaotic flood. After this map, NF enthusiasts dropped idea that cd find evidence in rocks and fossils. All that now lay in pre-Genesis history. The Rocks Don't Lie

    In C18 fossils with very delicately preserved features were found in several quarries around Europe. They were preserved in very thin layers of rock, which had obviously been deposited by very fine-grained mud, very slowly and in very calm water. These could not have been laid down by Noah's Flood - a brief and violent event.

    From mid-C18 on, idea that a single Flood event, whether a short-lived rise in ocean levels or a violent cataclysm, was dropped by scholars. There was simply too many and too varied examples of fossil deposition that clearly happened at different times and for different periods.

    Recognition of many extinct volcanoes in central France, yet no historical records or even local folklore to suggest that they had erupted in human times. Found that a lake which a Roman poet had recorded fishing on was in fact formed by a lava flow that had blocked the valley, so must have happened well before Roman times. Finally recognized that the ridge tops were also old lava flows, which meant that the lava had once flowed down prehistoric valleys, the surrounding hills of which had subsequently eroded away, leaving just the solidified lava to record where the valleys had once been. All implying unimaginable time to occur.

    1808 map of Paris geology by Cuvier showed layers of Coarse Limestone, full of fossil shells similar to marine molluscs today, which meant that a vanished sea had once extended across much of Paris. But there were also finer grain sandstones full of fossil shells of species that only grew in fresh water. Taken together, these meant that Paris had seen repeated but irregular alternation of marine and freshwater environments. And later, rivers had carved out valleys in these rocks, and filled them with alluvial gravels. Earth's Deep History

    You can see the evidence anywhere


    In NZ, we have a surfeit of geography and geology packed into small landmasses.




    Live in Auckland, which is built on a field of about 55 (hopefully) inactive volcanoes - last one erupted 650 years ago and now forms a massive island in middle of our harbour.



    The volcanoes erupted over fairly long time period - I live just above Panmure basin which is a caldera of two small collapsed vents which now form a tidal lagoon. The volcanoes don't completely cover the land - can still see parts of prehistoric landmasses - an alluvial plain - under the various lava flows, which themselves twine over other flows.

    Grew up in Christchurch, which is a city on eastern side of a huge alluvial plain.




    The hilly bit below ChCh is Banks Peninsula which is 2 very big old eroded volcanoes with collapsed calderas making Lyttelton and Akaroa harbours.

    The flat bit in brown is a shingle plain. We got lots of geog lessons in how it formed - the Southern Alps (mts in green) go up to 12340 feet high - they get heavy rain eroding slopes which dumps rocks into braided rivers which then have spread out over the plain. Classic size sorting - the big rocks close to the mts, getting smaller further east you go until get gravels and sand by time get to the coast.

    There is a shiat load of shingle making up the plains (about 1/2 a km thick); we can see by the size gradient that it has all come from eroding the Southern Alps, and it's easy to see that it's taken several million of years to deliver that much material.

    Fault Lines


    But the most interesting part of NZ is Southern Alps, which are right on a plate boundary.

    It's unusual bc a) both sides are on land and b) it's moving quickly - about 30 feet every 1000 years. It's ruptured 4 times in last 900 years - 1100, 1450, 1620 and 1717, so prob overdue for next one. It's a slip fault: the west side has moved about 480 kilometers north. The strata quite clearly show this on the surface - you can see a band of rocks come to an abrupt halt at the edge of the fault, then pick up the same band 100's of kilometers north.


    You can see the evidence


    The point of all this geog lesson is that there are geological features like these in most places - that have taken a very long time to form, and where multiple events have occurred, so you get volcanic lava overlaying eroded hills and then covered by limestone from sea creatures.












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