Born to a mining family in 1749, and educated at the University of Leipzig, Abraham Gottlob Werner established his reputation with a brief book, titled Von den Äußerlichen Kennzeichen der Fossilien, in 1774. By the turn of the 19th century, he was possibly the world's most famous Earth scientist. His enormous influence meant that he left both a good and bad legacy to the science of geology. On the up side, his 1774 book elaborated techniques for identifying minerals using human senses, drawing on his background in mining. His practical classification system appealed to a broad audience interested in learning more about geology. On the down side, he advanced the "Neptunian" view of the Earth, claiming that all rocks had been deposited in a primordial ocean. This view, which had been in existence before Werner promoted it, was accepted almost without question, and prevailed until overturned by James Hutton near the close of the 18th century.
Werner proposed new ways of thinking about geologic formations, redefining "formation" to refer not to the chemical makeup of a rock, but to the timing of its development. He defined formations as bodies of rock laid down in the same period, giving scientists a way of thinking about the rocks' histories. In arguing for a global ocean, however, Werner proposed "universal formations," i.e., everywhere on Earth, the same rock layers were deposited at the same times, as if the planet were an onion with global layers of skin. This idea was overturned long ago. While one area may accumulate rock layers through deposition of sediments, another area may lose rocks through erosion. Volcanic activity deposits ash and lava continually, but certainly not universally. One criticism of this hypothesis was that Werner hadn't traveled enough to verify it.
In the 18th century, rocks were explained in terms of the biblical flood, and were classified into three categories that most people associated with the biblical flood: "primary" for ancient rocks without fossils (believed to precede the flood), "secondary" for rocks containing fossils (often attributed to the flood itself) and "tertiary" for sediments believed to have been deposited after the flood. Werner didn't overturn the commonly held belief in the biblical flood, but he did recognize a different group of rocks that didn't fit this classification: rocks with a few fossils that were younger than primary rocks but older than secondary rocks. He called these "transition" rocks. Geologists of succeeding generations classified these rocks into the geologic periods still accepted today.
Narrative text and graphic design © by Michon Scott - Updated October 9, 2009