Cambrian Hotel Switzerland

Geochronology Geochronology is a geological calendar composed of named geological periods, in which rocks represented by geological columnar sections are deposited. At the early stage of geological development, people realized that it was necessary to divide the history of the earth into "chapters" that were easy to arrange. John Lyman made the earliest attempt at this division in 1756. He compiled a time representation based on the exposed rocks in Central Europe. Lyman identified three types of mountains and three types of rocks. After this pioneering work, Abraham Werner, a mineralogist in the18th century, put forward a four-fold division of rocks and ages. Werner believes that all rocks are precipitated from seawater, and they can be divided into four stages. Although Werner's theory of rock formation is no longer valid, his idea of establishing various time units still exists. With the progress of geological thought in19th century, geologists need a geochronology more. Their unremitting efforts have led to geological columnar profiles and chronologies widely used today.

One of the main problems of design chronology is to establish a standard for dividing the main periods of earth history. These natural periods are completely based on some geological events that are considered to be the most easily recognized in the rock record. Therefore, the period of orogeny and the change of ocean position is usually considered as an important enough sign to delimit the boundaries between times in the chronology. However, now we know that orogeny may be confined to a continent, and the "advance and retreat" of the ocean has no exact regularity. Therefore, it is the basic principle of correlation and superposition of fossil assemblage sequences in rocks to establish the standard rock columnar profile and geochronology currently used.

The time unit in geochronology has the same name as the rock unit originally used to distinguish geological columnar sections. Therefore, people can say CAMBRIAN (geochronology) or CAMBRIAN rocks (geological columnar sections). The largest unit of time is the generation. Generation divides discipline, and discipline divides the world.

Different from the day and month in the standard calendar, geological time units are artificially divided, and the length of time experienced is also different, because there is no way to know how long each generation, era or world contains. Nevertheless, geochronology has given geoscientists a concept of time. For example, they say that a rock is in Cretaceous, which means that it was formed in Cretaceous about 65 million years ago.

The five generations in geochronology have their own names to describe the degree of biological development that represents the characteristics of that generation. For example, Paleozoic literally means "ancient creatures", indicating that this generation of creatures is relatively simple and is an ancient stage of their development. The literal meaning of each generation and its name can be arranged as follows in order from newest to earliest:

Cenozoic-modern creatures

Mesozoic-mesozoic organisms

Palaeozoic ancient creatures

Proterozoic-an ancient creature

Archaean creatures-primitive creatures

Archean and Proterozoic rocks are usually called Precambrian rocks. Most Precambrian rocks have been deformed and are very old; So the record of this historical stage of the earth is difficult to explain. Precambrian represents the geological period from the beginning of earth history to the earliest CAMBRIAN rocks containing fossils, so it represents about 85% of the total geological time.

Most people in each generation are named after the place where their rocks were first studied.

Paleozoic is divided into seven periods (the oldest is at the bottom of the table). The sources of these cycles and their names are as follows:

Permian-named after Perm province of the Soviet Union.

Pennsylvania-named after Pennsylvania, USA.

Mississippi-named after the upper Mississippi valley (Carboniferous used by European geologists includes Pennsylvania and Mississippi in North America).

Devonian-named after Devon, England.

geological time scale

The order of geological chronological units. The latest time unit is at the top of the histogram, while the earliest time unit is at the bottom of the graph.

Geology: the study of the origin, composition, structure and history of the earth and its inhabitants. The name comes from the Greek geo plus logos, and the field of geology is very extensive, which makes it divided into two branches: physical geology and historical geology. Physical geology studies the composition and structure of the earth, and various movements in and on the crust are now developing the earth's surface.

Silurian-An ancient tribe named Silurian in Great Britain.

Ordovician-named after an ancient tribe in Great Britain.

CAMBRIAN-named after the Latin Cambria, which means Wales.

Mesozoic period and its name come from:

Cretaceous-from Latin Creta, which means chalk.

Jurassic-Naming of Jura Mountain between France and Switzerland

Mountains)

Triassic (Triassic)-Derived from Latin Trias, which means.

The name of the Cenozoic comes from an outdated classification system, which divides all the rocks on the earth into four groups. The following two split periods are the two surviving periods still in use in the system:

Fourth order-it means fourth derivative.

Third order-it means the third derivative.