Posted by: Rob Viens | July 20, 2012

Jurassic Dreams with Leopold von Buch

The quiet days at sea made it such that Darwin didn’t have much to talk about other than the weather. At this point the Beagle was entering the “mid-latitudes” – about the equivalent of southern Florida in the northern hemisphere. Being July, it was firming in the heart of the southern winter, and the temperatures had dropped from what Darwin had been used to further north. On July 20th he wrote:

“There is a fine breeze but we can hardly keep our course.— At noon we were 160 miles from Cape St Mary.— We have experienced to day a most complete change of climate.— From the joint cause of shoal water & probably a current from the South, the temperature of the sea at noon was 61°½, it being in the morning 68°½— The wind felt quite chilling; the thermometer standing at 59°.” (July 20)

So not much left to do except take advantage of that Beagle library (highlighted a couple of days ago).  Darwin admits:

“By the time we arrive in harbor, we shall have made a very bad passage & I am sure to me a very tedious one.— The only thing I have been able to do is reading Voyages & Travels.— these are now to me much more interesting than even novels.” (July 20)

Among the “voyages & travels” stowed away on the Beagle was the adventures of Christian Leopold von Bush and his Travels Through Norway and Lapland. (Darwin had a copy that was translated into English by John Black.) Von Buch was a German naturalist who studied alongside Darwin’s hero Alexander von Humboldt. While Humboldt made his fame in the New World, von Buch concentrated on studying central Europe and Scandinavia.  The book that Darwin had on board recounted the German’s 2-year exploration of Norway and Lapland, during which von Buch made careful observations of the climate, botany and geology of the region.  His observations helped provide evidence for major glacial “ice ages” (later proposed and championed by Louis Aggasiz).  For example, he recognized that large erratics found in Germany matched source rocks in Norway (these rocks were carried vast distances by the ice sheets).  He also noted that Sweden was “rising” out of the sea, and although I don’t think he proposed a cause, we now know that this “rebound” is due to the removal of the massive glacial ice sheets about 10,000 years ago. (This is like taking your weight off a mattress and watching it slowly rebound back into shape.  Only in the case, rock moves more slowly, so the rebound takes many thousands of years.)

A young Leopold von Buch (I believe from the 1820’s) – from History of Geology and Paleontology to the End of the Nineteenth Century.

However, von Buch’s most noteworthy contribution (at least the one that he is probably the most famous for) is defining the Jurassic Period.  Technically he described and defined the rocks in Germany that formed during this period – called the Jurassic System. It was these “systems” of rocks that later became the type-sections for specific time periods and ultimately lent their names to the periods on the geologic time scale. So in effect, von Buch can be credited with “discovering” the Jurassic.  But did anyone mention this in Jurassic Park?  No….no one cares about the poor stratigraphers…

Leopold von Buch in the 1850’s by Carl Jospeph Begas

Von Buch also made several other contributions to geology.  When working on the volcanoes of the Canary Islands, he coined the word “caldera” (Spanish for bowl). These are large volcanic basins formed by the collapse of the surface after magma is ejected from a volcano. In addition he studied Vesuvius in Italy, developing a strong sense of how igneous rocks formed from cooling magma.  This may seem obvious, but von Buch studied nder Abraham Gottlob Werner – the leading proponent of the idea that basalt (and other igneous rocks) formed at the bottom of an ocean. He was what was called a” Neptunist” – actually he was king of the Neptunists.  Like Darwin, von Buch would have had to stand by his evidence to go against the mainstream teaching in Germany at the time and propose a volcanic origin of the rocks.  This ability to let the evidence speak for itself, without getting caught up in preconceived notions, is one of the true indications of a great scientist. (Be sure to see Neptunists, Plutonists and the Significance of Granite for more on this story.)

A regional geologic map by von Buch titled “Esquisse d´une carte geologique de la parte meridionale du Tyrol”

In 1832, while Darwin was cruising the coast of South America, von Buch was publishing a geologic map of Germany.  As the first geologic map was published less than 25 years before in England, this had to have been one of the first (if not the first) complete geologic map of Germany. (RJV)

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