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Re: Cables, the debate

Humm, I know of a spring here in Florida called Warm mineral springs(Warm
hardwater/high CO2), they have a few plants but they don't grow where the
water perculates up through the substrate. They did find some 12,000yo Human
Indian and saber tooth bones/remains. It's a neat spring, deep, good for
scuba, bad for plants. Water is fairly warm vs the average spring here.
Some springs go very deep here and some also in other regions do go very
deep(10,000ft etc).

Sure, not ALL
ecosystems are like this, but maybe some places have warm groundwater
seeping UP from below the substrate. The sun is not directly involved in
this - consider magma (magna?) near the surface.

Really? How much magma would I dose?:-) Volcanic Vals? Magamatic Mayaca? I'm using Florida as an example since it has year round plants, 100'S of springs with brackish, fresh water w/soft, medium and hardness, sulfur, warm, most are around 68-73F year round, no variation to speak of temperature/chemical wise. This makes them ideal natural experiment laboratories.

But in the winter, the spring is warm compared to the surrounding air but
the water temp stays very constant regardless.

This is one reason I want folks to come here to see all the variation in
habitat and wonder why this might be. 8000 lakes, many rivers/streams.
Most with plants, no winter ice etc.

From what I have learned doing 2 years of A-level Geology (i.e. not a lot),
most underground warmth, that causes warm mineral springs etc, does not come from magma except in active volcanic areas (Iceland, Yellowstone Park) . Most is simply caused by the geothermal gradient. Firstly, rock temperature at a depth of only 30 feet or less at are effectively constant, regardless of seasonal changes, so some people use boreholes to provide warmth in winter. Secondly, the average geothermal gradient of the Earth's crust is about 1 degree celcius per 100 foot, so water would be boiling 10000ft down. Secondly, some areas of the world have much steeper geothermal gradients, caused by radioactive decay of trace isotopes in relatively new rocks such as recent granites and recent sedimentary rocks. In fact, radioactive isotopes such as potassium, radium and uranium in the crust and upper mantle provide most of the heat for all the volcanism on Earth, which is (relatively) shallow.
I am not, however, suggesting that we replace heating coils with strips of radioactive material.

Andrew McLeod
thefish at theabyssalplain_freeserve.co.uk