What Is a Geologic Map?

Geological map is a kind of map that shows the formation age of sedimentary rock layer, igneous rock body, geological structure and other various geological bodies and geological phenomena with a certain legend on a scale topographic map. It is a general term for maps representing crustal surface lithology, lithology, stratigraphic age, geological structure, magmatic activity, and mineral distribution. Thematic map showing the geological composition and structural characteristics of the mapping area. Usually there are general geological maps, geotectonic maps, paleogeographic maps and so on. ^[1]

Geological maps from the beginning of the germination stage in the middle of the 18th century (1726) to the beginning of the 19th century. Based on the order of fauna, the Englishman Smith W. (1769 ~ 1839) established the method of "identifying formations with fossils" and in 1815 The first British geological map with rock stratigraphic units, paleontological fossils and geological ages was published in the year, laying the foundation for modern geological maps. This traditional method has continued to improve geological mapping for more than 150 years. Until the "International Stratigraphic Guide" issued by the International Stratigraphic Commission in 1976, geological mapping was transformed from traditional methods to modern stratigraphic methods, including multiple stratigraphic unit divisions, the application of the universal principle of the timeliness of rock stratigraphic units, and so on. Digital geological maps are generated from a wide range of applications. Geological maps have made tremendous contributions to human socio-economic and cultural development. ^[2]

Geological maps began in the late 18th and 19th centuries with British geologist William

Divided into: rough, regional, detailed and specialized geological maps; divided into small (1 / 500,000 and smaller), medium (1/25 ~ 1 / 200,000), large scale according to scale (150,000 / larger) geological map. According to the content, it can be divided into: bedrock geology map, geology and mineral map, lithology-lithology distribution map, structural geology map, mineral map, quaternary geology map, paleogeography map, hydrogeology map, engineering geology map, and environmental geology map. Wait. With the development of basic geological disciplines such as geotectonics, tectonic geology, petrology, and paleontology in theoretical and research methods, it has also profoundly affected the content of geological maps. For example, the rise of plate tectonics has given new understanding and new explanations to many tectonic phenomena; new research methods such as paleomagnetic research, palaeobiological research, trace element analysis, and absolute age determination have greatly enriched the content of geological maps. ; The wide application of geophysical and geochemical methods, as well as new technologies and methods such as remote sensing and computers, has improved the quality of geological maps, accelerated the speed of mapping, and expanded the scope of geological maps. With the further needs of human society and production, the theme of current geological maps has shown a trend of expanding to celestial geological maps, marine geological maps, and urban environmental geological maps.