EXPO: "Down to Earth - Geological maps"
Modern geographical maps were published as the "Carte Géologique de la France" at 1:320,000 scale and as the "Carte Géologique Detaillé de la France" at 1:80,000.
Although the 1:80,000 scale was formally ended in 1925 and replaced by the 1:50,000 scale, it continued to be produced until 1971.
The little but interesting exposition will include some fine geological maps of France, European countries and North America mainly from the 19th century.
There is something about geological maps from the early twentieth century! Their colors seem more vivid than those of modern maps. Even their legends are more interesting: geological maps are special-purpose maps made to show geological features. Rock units or geologic strata are shown by color or symbols to indicate where they are exposed at the surface.
Bedding planes and structural features such as faults, folds, foliations, and lineations are shown with strike and dip or trend and plunge symbols which give these features three-dimensional orientations.
Stratigraphic contour lines may be used to illustrate the surface of a selected stratum illustrating the subsurface topographic trends of the strata. They offer a glimpse of the transportation infrastructure (steam and electric railroads, trails, ferry landings), landscape features that may not be visible today (salt marshes, swamps, tidal flats, escarpments, rock outcrops), and geology (stony and gravelly areas, quarries).
There are colors for different ages of rocks, patterns for different kinds of rock, and lines for faults, elevation and boundaries between rock layers. Each colored area on the map also has a a letter symbol, which you can see in the explanation boxes.
Among the various branches of science, the earth sciences, especially geology, are most dependent on maps. Geology was the exciting new science of the nineteenth century, much like space exploration or biotechnology in the twentieth. New concepts appeared of unimaginably vast spans of time, of strange extinct creatures, of systematic ways of exploring for economic minerals.
History
The world's oldest geological map ever found was drawn around 1150 BC to document an expedition by a pharaoh to retrieve building stone in Egypt.
This papyrus map discovered around 1820 and now in the Egyptian Museum in Turin, Italy, illustrates the topography and geology of Wadi Hammamat in the mountains of the central Eastern Desert of Egypt.
It accurately depicts the areal distribution of sedimentary and igneous/metamorphic rocks, which are shown as black and pink hills, respectively. The ancient map also shows the gold-working settlement at Bir Umm Fawakhir, the gold-bearing quartz veins on the adjacent mountain,
This papyrus is the oldest surviving geological map in the world, and it predates by 29 centuries the next oldest known geological map
1741 - The first real "Carte géologique de la France" (Geological map of France)" on a scale of 1:500,000 was presented to the Académie des Science. Its object was "to represent graphically, by conventional colors and by some other signs.
1746 - Jean-Étienne Guettard, medical doctor, botanist and mineralogist, Réaumur's assistant and Lavoisier's friend, published a book entitled “Mémoire et carte minéralogique sur la nature et la situation des terrains qui traversent la France et l'Angleterre”.
When presenting his thesis to the Royal Academy of Sciences on 19 February 1746, Guettard clarified his intention: “I proposed to show by this map that there is a certain regularity in the distribution of stones, metals and most other fossils”. In fact, on his map, in addition to the specific indications already mentioned, there are three more or less concentric “bands”, corresponding to “sandy, marly or slatey” soils that connect a large part of the Paris basin to the Kent, Middlesex and Norfolk regions in England, underneath the Channel and the Pas-de-Calais region.
This was the first attempt at geological mapping, although still in a very clumsy and rudimentary way.
1807 - A small but creditable geological map of the United States was produced in 1809 by William Maclure. In 1807, Maclure undertook the self-imposed task of making a geological survey of the United States. He traversed and mapped nearly every state in the Union. During the rigorous two-year period of his survey, he crossed and recrossed the Allegheny Mountains some 50 times.
1815 - The first geologic map of Great Britain was created by William Smith in 1815.
Arguably the most famous map in the history of geology is this one, published in 1815 by William Smith, showing the stratification of England, Wales and part of Scotland. For the first time ever, this map presented a detailed overview of the geology of an entire country.
It set the standard for all geology maps that have followed. And it turned geology into a ‘practical’ science – helping industrialists locate mineable coal seams, for example. Indeed, this was “The Map that Changed the World,” as described in a bestselling book of that title.
1816 - The first geological map of France at a scale of 1:500,000
By the second half of the 19th century most European nations had detailed geographical maps. At the end of the century, these surveys were bought together in the "Carte Géologique Internationale d'Europe" (1:1,500,000), which was one of the first important international maps made with the cooperation of various governments. For this map, an international color scheme was adopted to replace the arbitrary colors of earlier maps.
