Log Day 15: Mid-Atlantic geology - by Alan
Pipistrelle - where are we now?
Bob and Elaine Hazell
Mon 7 Dec 2009 23:46
15:06.28N 53:35:90W
You may not think there is much geology out here, but actually there
is some. We have just crossed the Mid-Atlantic Ridge lying 4000
metres below us on the ocean floor. It runs roughly north-south over the whole
length of the Atlantic. It is a several kms wide volcanic-type ridge
that is producing new oceanic crust at the rate of about 1-2 cm per year. The
new crust spreads out from the ridge in both directions, forming abyssal plains,
imperceptibly sloping down away from the ridge. It's undetectable to us on the
surface, but satellite geoid measurements would show it up as an height
anomaly.
Interestingly, geological evidence from the ocean floor
confirms that the earth's magnetic field does reverse polarity from time to
time. The North Pole becomes the South Pole and vice versa. A scary thought for
us mariners, but it is believed that the change would be gradual rather than
flip overnight. But who really knows and why does it
happen?
We have been two weeks at sea now and the mood on board has become noticeably calmer, more relaxed, and more contemplative, missing loved ones back at home and in faraway places (Nick's wife Anne is currently in India). Are we nearly there yet?
Bearing to St Lucia waypoint: 263 degrees
true
Distance to waypoint: 432 nautical
miles
The wind continues to be unbelievably consistent. It has not
varied from an overall ENE direction for two weeks now, with an equally
consistent wind strength of broadly force 5/6. Consequently, our boat speed has
not dropped below 5 knots at any stage of the trip. We just keep rolling
westwards.
Navigation decisions for
the approach to the finishing line at St Lucia are now becoming critical. Here
is a photo of the team in action, studying mr.grib's latest
predictions.
Roll on Rodney Bay, St
Lucia, and a large bowl of french fries!
BFN
Bob, Elaine, Nick, Alan and Paul
