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Hi Will,

As promised, here are just few words about columnar jointing in basalt
that you can observe from your hotel right behind the waterfall:
columnar jointing forms in lava flows in most cases, and is somewhat a
rather rare feature. Columns are straight and regular (but sometimes
curved) with 4 to 7 faces (check the steps along the steep track going
down to the water fall!). It is commonly interpreted as resulting from
rapid cooling from the top downward, most likely in the presence of water.

Below the columnar jointing unit is a different, more altered (orange
color is due to the presence of clay minerals that forms during
alteration) unit with bombs and scoriae. Unlike columnar jointing, which
result from effusion of basaltic lava, such feature results from a more
a explosive event that occurred prior to eruption of columnar basalt.

These 2 units can be seen in the front page of your brochure. Both
deposits most likely results from the (extinct) volcanic activity of the
Porvenir Volcano.

Hope this helps - including this in your website will attract thousands
of Geologists! :-)

all the best

Damien

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