Earth Science Today
Russ Colson
Minnesota State University Moorhead
 
Historical Note:
Scientists have not always known that basalt, a dark layered rock, formed from volcanoes.  In the 1700's this interpretation was very controversial.  Some people thought that the rocks crystallized out of sea water.  Evidence that they are volcanic includes presence of bubbles in the rock (how could you get bubbles in a rock that was not melted?), the crystalline nature of the rock (individual crystals are grown together as though crystallized from a melt), and the similarity of basalt layers to rocks observed to come from volcanoes.  But the matter was not resolved until basalt was physically associated with volcanoes.

In 1774, after eleven years of careful field studies, Desmarest (1725-1815) published his observations and interpretations of the basalt layers and their clear association with volcanoes of the Auvergne district of central France.  His words reflect the measured excitement of his discovery:

"I followed the thin sheet of black stone and recognised in it the characters of a compact lava.  Considering further the thinness of this crust of rock, with its underlying bed of scoriae, and the way in which it extended from the base of hills that were obviously once volcanoes, and spread out over the granite, I saw in it a true lava-stream which had issued from one of the neighbouring volcanoes.  With this idea in my mind, I traced out the limits of the lava, and found again everywhere in its thickness the faces and angles of the columns, and on the top their cross-section, quite distinct from each other.  I was thus led to believe that prismatic basalt belonged to the class of volcanic products."

Sometimes, people think that scientific truth is defined by influential figures in the science community who effectively declare their version of truth.  Science in this model becomes "truth by authority" and rests more on faith in the scientists than on scientific investigation.  An interesting footnote on how scientist resolve conflict is found in the story of Desmerest.

Nicholas Desmarest was a key figure in this famous controversy in the 1700's.  At that time, the argument raged over how rocks form, whether from volcanoes or seawater.  His key contribution was to prove an association between basaltic rocks and volcanoes in the Auvergne district of central France.  But, when he was asked in his old age what the "truth" was, he answered simply "Go and see!"

Science is about observations that anyone is free to check out.

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