Gottlob Werner (1749–1817), who has been called the father of geology. Werner
and Bergman exchanged both letters and mineral samples [10].
On the other side was James Hutton (1726–1797), one of the important figures in
the development of the plutonist school. Although Bergman is rarely mentioned in
the history of geology, Werner was clearly inspired by Bergman, but also Hutton
derived some of his ideas from Bergman [11]. In turn it has been pointed out [12]
that Bergman probably derived some of his ideas on the formation of layered rocks
from Johan Gottlob Lehman (1719–1767) [13]. Bergman was also clearly inspired
by Linnaeus’ geological writings, especially when it came to the question of water
decrease [14].
In principle, Bergman thought that rocks had formed by sedimentation of particles suspended in water and by crystallisation of dissolved matter from water. The
crystallisation hypothesis was introduced in the second edition of his Physical
Description of the Earth, published after he became professor of chemistry [15].
Other rocks had formed by volcanic activity, and Bergman clearly suggested that
Earth had undergone much change since its first formation and not only through the
action of water. He also clearly recognised that the lower layers in mountains were
older than the upper layers.
The mountains in Bergman’s home province Västergötland, e.g. Billingen
(Fig. 7.1) and Kinnekulle, caused considerable problems for Bergman. They are
mainly sedimentary, consisting of sandstone resting on the bedrock, followed by
alum shale, lime stone and shale deposited from Cambrian to early Silurian but
covered with a layer of volcanic basalt from Permian. It is this basalt cap that has
protected the underlying layers from erosion and the destructive effects of the
glacial periods. The lower layers contain fossils and Bergman correctly recognised
them as sedimentary. Bergman, however, did not believe in widespread volcanism
and thus had to propose a sedimentary origin for the basalt as well [16]. The origin
of volcanism was unknown, but was believed to be caused by chemical reactions or
combustion of coal deep underground, thus it was unlikely to occur other than in
special locations such as Iceland and Italy. In Sweden, there were absolutely no
signs of volcanic activity. The igneous nature of basalt was not perhaps first
recognised by Beddoes in 1791, a few years after Bergman’s death [17].
In the fall of 1768, a year after becoming professor of chemistry, Bergman
published a paper on the mountains of Västergötland [18]. Bergman had travelled
around exploring the mountains over the years and noted that they all consisted of
the same layers in the same order. It is interesting to note that Bergman’s discussions on the chemical composition of the different layers are strictly qualitative, and
he was far from the expert in chemical analysis he would be a decade later. He had
learned to use the blow-pipe (Sect. 23.5) and treated the minerals with acids, but did
not report more thorough analyses. For example, when discussing lime stone, he
wrote that “It holds something ferrous,
1 as it turns yellow or rusts with time, and is
drawn to the Magnet after burning”. In his later writing, he would never use such a
vague description, but would more probably report the percentage of iron oxide in
1
“järnaktigt” in the original text, meaning something iron-like.
84
7 Bergman’s Geological Work
and Bergman exchanged both letters and mineral samples [10].
On the other side was James Hutton (1726–1797), one of the important figures in
the development of the plutonist school. Although Bergman is rarely mentioned in
the history of geology, Werner was clearly inspired by Bergman, but also Hutton
derived some of his ideas from Bergman [11]. In turn it has been pointed out [12]
that Bergman probably derived some of his ideas on the formation of layered rocks
from Johan Gottlob Lehman (1719–1767) [13]. Bergman was also clearly inspired
by Linnaeus’ geological writings, especially when it came to the question of water
decrease [14].
In principle, Bergman thought that rocks had formed by sedimentation of particles suspended in water and by crystallisation of dissolved matter from water. The
crystallisation hypothesis was introduced in the second edition of his Physical
Description of the Earth, published after he became professor of chemistry [15].
Other rocks had formed by volcanic activity, and Bergman clearly suggested that
Earth had undergone much change since its first formation and not only through the
action of water. He also clearly recognised that the lower layers in mountains were
older than the upper layers.
The mountains in Bergman’s home province Västergötland, e.g. Billingen
(Fig. 7.1) and Kinnekulle, caused considerable problems for Bergman. They are
mainly sedimentary, consisting of sandstone resting on the bedrock, followed by
alum shale, lime stone and shale deposited from Cambrian to early Silurian but
covered with a layer of volcanic basalt from Permian. It is this basalt cap that has
protected the underlying layers from erosion and the destructive effects of the
glacial periods. The lower layers contain fossils and Bergman correctly recognised
them as sedimentary. Bergman, however, did not believe in widespread volcanism
and thus had to propose a sedimentary origin for the basalt as well [16]. The origin
of volcanism was unknown, but was believed to be caused by chemical reactions or
combustion of coal deep underground, thus it was unlikely to occur other than in
special locations such as Iceland and Italy. In Sweden, there were absolutely no
signs of volcanic activity. The igneous nature of basalt was not perhaps first
recognised by Beddoes in 1791, a few years after Bergman’s death [17].
In the fall of 1768, a year after becoming professor of chemistry, Bergman
published a paper on the mountains of Västergötland [18]. Bergman had travelled
around exploring the mountains over the years and noted that they all consisted of
the same layers in the same order. It is interesting to note that Bergman’s discussions on the chemical composition of the different layers are strictly qualitative, and
he was far from the expert in chemical analysis he would be a decade later. He had
learned to use the blow-pipe (Sect. 23.5) and treated the minerals with acids, but did
not report more thorough analyses. For example, when discussing lime stone, he
wrote that “It holds something ferrous,
1 as it turns yellow or rusts with time, and is
drawn to the Magnet after burning”. In his later writing, he would never use such a
vague description, but would more probably report the percentage of iron oxide in
1
“järnaktigt” in the original text, meaning something iron-like.
84
7 Bergman’s Geological Work