5.4.1. Relative dating

Relative dating

The dating or relative geochronology is sort geological events , saying what happened before and what happened after, without assigning a specific date in millions of years.

The layers are horizontal layers that are deposited sediments in the bottom of a sedimentary basin. The strata contain information about the environment, age, and circumstances that characterized the environment in which they were deposited. It could be said that they are the pages of the book "History of the Earth" that we must "read" to know it. Although we do not have all these "pages", we can base ourselves on a series of geological principles that will allow us to date, in a relative way, the main geological events.

Principle of superposition of strata

The sediment layers are deposited in a temporal sequence, in which the oldest ones are in a lower position than the most recent ones.

Therefore, if there has been no deformation, the lower layers were deposited earlier than those above, so they are older. On the other hand, if there has been deformation, the folds or faults may have caused changes that make older layers are arranged above more modern ones.

By Kurt Rosenkrantz [CC BY-SA 3.0], via Wikimedia Commons

Interactive activity: Order the strata from oldest to most modern .

Geological Song: Principle of Overlapping Strata and How to Recognize If the Stratum is in a Normal or Inverted Position .

Principle of faunal succession

The strata that were deposited at different geological times contain different fossils, due to the continuous and irreversible nature of biological evolution.

The fossils, in principle, the same age as the strata in which they are, so according to the principle of superposition of strata, those in the lower strata will also be older than those in the upper strata.

As the strata containing the same type of fossil were deposited at the same time, if we know the relative age of the fossil, we can know the age of the stratum that contains it, even if it is elsewhere.

By Kurt Rosenkrantz [CC BY-SA 3.0], via Wikimedia Commons

Principle of superposition of events

A geological process that affects some materials is always after them, and before the materials that it does not affect and the processes that affect it.

For example, if a rock appears folded, the rock will be older than the fold. Or if it is a short stratum to another, the one that appears cut is the oldest.

Principle of uniformism or uniformitarianism

The uniformism or uniformitarianism is the principle according to which the natural processes that acted in the past are the same that act in the present and with the same intensity.

This principle states that geological processes (erosion, plate movement, etc.) have remained uniform throughout geological time.

Principle of actualism

The actualismo can be summed up with the phrase "the present is the key to the past". It means that the processes that take place today (magmatism, sedimentation, earthquakes, etc.) are the same that have happened throughout the history of the Earth.

Thus, by studying the present we can obtain information about what happened in the past and get an idea of the changes that have occurred on Earth since its formation.

Ondulaciones en la playa

The ripples in the sand on the beach, current and fossil, are similar .

Interactive activity: Biological or geological processes?.

Interactive activity: Geological principles.

Interactive activity: More geological principles.

Animation: How to make geological sections from geological maps.

Licensed under the Creative Commons Attribution Share Alike License 4.0

BIOLOGÍA - GEOLOGÍA . COM
1st ESO	3rd ESO	4th ESO	Biology 2nd Baccalaureate
Index by courses	Forums	Geología 2º Bach.

Skip navigation Biology and Geology 4th ESO Biology and Geology 4º ESO 1. The cell 1.1. Levels of organization of living beings 1.2. Cell theory 1.3. The cell 1.3.1. Prokaryotic cell 1.3.2. Eukaryotic cell 1.3.2.1. Common organelles 1.3.2.2. Organelles of the animal cell 1.3.2.3. Plant cell organelles 1.4. Cell nucleus 1.5. Vital functions of cells 1.6. Cellular cycle 1.6.1. Mitosis 1.6.1.1. Cytokinesis 1.6.2. Meiosis 1.6.2.1. Meiosis I. First meiotic division 1.6.2.2. Meiosis II. Second meiotic division 1.6.2.3. Result of meiosis 1.6.3. Differences between mitosis and meiosis 1.6.4. Biological importance of mitosis and meiosis 1.7. Bibliography 2. Genetic information 2.1. Nucleic acids 2.1.1. DNA 2.1.2. RNA 2.1.3. Control of protein synthesis 2.2. DNA and molecular genetics 2.3. Gene concept 2.4. Replication of DNA 2.5. DNA to RNA transcription 2.6. Genetic code 2.7. Translation of RNA to proteins 2.8. Mutations Relations with evolution 2.9. Biotechnology 2.10. Genetic engineering: techniques and applications 2.10.1. Cloning 2.10.2. Human Genome Project 2.11. Bioethics 2.12. Bibliography 3. Biological inheritance 3.1. The inheritance and transmission of characters 3.2. Introduction and development of Mendel's Laws 3.2.1. Mendel's First Law 3.2.2. Mendel's second law 3.2.3. Mendel's third law 3.3. Chromosomal basis of Mendel's Laws 3.3.1. Exceptions to Mendel's Laws 3.3.2. Chromosomal theory of heredity 3.3.3. Genetics concepts 3.3.4. Types of inheritance 3.4. Human genetics 3.4.1. Inheritance of blood groups 3.4.2. Sex inheritance 3.4.3. Sex-linked inheritance 3.4.4. Heredity influenced by sex 3.5. Genetics problems 3.5.1. Inheritance of a character (problems solved) 3.5.1.1. Albinism (problems solved) 3.5.1.2. Rh groups (problems solved) 3.5.1.3. Eye color (problems solved) 3.5.1.4. More inheritance problems of a character 3.5.1.5. More inheritance problems of a character 3.5.1.6. More inheritance problems of a character 3.5.1.7. More inheritance problems of a character 3.5.2. Two-character inheritance (problems solved) 3.5.2.1. More two-character genetic inheritance solved problems 2 3.5.2.2. More two-character genetic inheritance solved problems 3 3.5.2.3. More two-character genetic inheritance solved problems 4 3.5.2.4. More two-character genetic inheritance solved problems 5 3.5.3. Codominance and intermediate inheritance (problems solved) 3.5.3.1. More codominance and intermediate inheritance problems 2 3.5.4. Sex-linked inheritance (problems solved) 3.5.4.1. Color blindness or daltonism (problems solved) 3.5.4.1.1. More color blindness problems or daltonism 3.5.4.2. Hemophilia (problems solved) 3.5.4.3. Sex-linked inheritance (two characters) 3.5.4.4. More sex-linked inheritance problems 3.5.5. Sex-influenced inheritance (problems solved) 3.5.6. Multiple alleles (problems solved) 3.5.6.1 AB0 blood groups (problems solved) 3.5.6.1.1. More AB0 blood group problems solved 2 3.5.6.1.2. More AB0 blood group problems solved 3 3.5.7. Genealogical trees 3.5.7.1. Family Trees 2 3.5.7.2. Family Trees 3 3.6. Bibliography 4. Origin and evolution of living beings 4.1. Hypothesis about the origin of life on Earth 4.2. Evolution of living beings 4.3. Theories of evolution 4.3.1. Lamarck 4.3.2. Darwin and Wallace 4.3.3. Neo-Darwinism 4.3.4. Other evolutionary theories 4.4. Evidences of evolution 4.4.1. Anatomical evidence of evolution 4.4.2. Embryological evidence of evolution 4.4.3. Paleontological evidence of evolution 4.4.4. Biogeographic evidence of evolution 4.4.5. Biochemical evidence of evolution 4.5. Mechanisms of evolution 4.5.1. Genetic variability 4.5.2. Natural selection 4.5.3. Consequences of evolution 4.5.3.1. Adaptation of organisms 4.5.3.2. Speciation 4.5.3.3. Species diversification 4.6. Human evolution: process of hominization 4.6.1. Primates 4.6.2. Hominids 4.6.3. The human being 4.7. Bibliography 5. The history of the Earth 5.1. The origin of the Earth 5.2. Earth, a changing planet 5.3. Geological time: historical ideas about the age of the Earth 5.4. Dating methods 5.4.1. Relative dating 5.4.1.1. Geological history exercises - relative dating 5.4.2. Absolute dating 5.5. Fossils 5.5.1. Fossils in Aragon 5.6. Geological history of the Earth 5.6.1. Precambrian 5.6.2. Phanerozoic 5.6.2.1. Paleozoic 5.6.2.2. Mesozoic 5.6.2.3. Cenozoic 5.7. Bibliography 6. Structure and dynamics of the Earth 6.1. Earth study methods 6.1.1. Seismic discontinuities 6.2. Structure and composition of the Earth 6.2.1. Geochemical model 6.2.2. Dynamic model 6.3. Bibliography 7. Plate tectonics 7.1. From continental drift to plate tectonics 7.1.1. Wegener continental drift 7.2. Plate Tectonics and its manifestations 7.2.1. Lithospheric plates 7.2.2. Oceanic ridges 7.2.2.1. Expansion of the ocean floor 7.2.3. Ocean trenches 7.2.4. Transforming faults 7.2.5. Formation of mountain ranges 7.3. The Wilson cycle 7.4. Rock deformation 7.4.1. Folds 7.4.2. Faults 7.4.3. Joints 7.4.4. Mixed structures 7.5. Bibliography 8. Ecosystems 8.1. Ecosystem structure 8.1.1. Types of ecosystems 8.1.1.1. Aquatic ecosystems 8.1.1.2. Terrestrial ecosystems 8.1.1.2.1. Urban ecosystems 8.2. Components of the ecosystem: community and biotope 8.2.1. Biotope 8.2.2. Biocenosis or community 8.3. Habitat and ecological niche 8.4. Limiting factors and adaptations 8.5. Tolerance limit 8.6. Trophic levels 8.7. Trophic relationships: chains and networks 8.8. Ecological pyramids 8.9. Self-regulation of the ecosystem, the population and the community 8.9.1. Intra and interspecific relationships 8.10. Matter cycle and energy flow 8.11. Biogeochemical cycles 8.11.1. Carbon cycle 8.11.2. Nitrogen cycle 8.11.3. Phosphorus cycle 8.12. Ecological successions 8.13. Bibliography 9. Resources and environmental impacts 9.1. Human activity and the environment 9.2. Natural resources and their types 9.3. Environmental impacts 9.3.1. Pollution of the atmosphere 9.3.1.1. Air pollutants 9.3.1.2. Acid rain 9.3.1.3. The smog 9.3.1.4. Ozone layer hole 9.3.1.5. Increased greenhouse effect 9.3.1.6. Climate change 9.3.2. Noise pollution 9.3.3. Light pollution 9.3.4. Water contamination 9.3.4.1. Water pollutants 9.3.4.2. Water eutrophication 9.3.4.3. Aquifer reduction 9.4. Soil 9.4.1. Soil contamination 9.5. Main environmental problems of Aragon 9.6. Overpopulation and its consequences 9.7. Waste and its management 9.8. Bibliography and student work « Previous \| Next » 5.4.1. Relative dating Relative dating The dating or relative geochronology is sort geological events , saying what happened before and what happened after, without assigning a specific date in millions of years. The layers are horizontal layers that are deposited sediments in the bottom of a sedimentary basin. The strata contain information about the environment, age, and circumstances that characterized the environment in which they were deposited. It could be said that they are the pages of the book "History of the Earth" that we must "read" to know it. Although we do not have all these "pages", we can base ourselves on a series of geological principles that will allow us to date, in a relative way, the main geological events. Principle of superposition of strata. Principle of faunal succession. Principle of superposition of events. Principle of uniformism or uniformitarianism. Principle of actualism. Principle of superposition of strata The sediment layers are deposited in a temporal sequence, in which the oldest ones are in a lower position than the most recent ones. Therefore, if there has been no deformation, the lower layers were deposited earlier than those above, so they are older. On the other hand, if there has been deformation, the folds or faults may have caused changes that make older layers are arranged above more modern ones. By Kurt Rosenkrantz [CC BY-SA 3.0], via Wikimedia Commons Interactive activity: Order the strata from oldest to most modern . Geological Song: Principle of Overlapping Strata and How to Recognize If the Stratum is in a Normal or Inverted Position . Principle of faunal succession The strata that were deposited at different geological times contain different fossils, due to the continuous and irreversible nature of biological evolution. The fossils, in principle, the same age as the strata in which they are, so according to the principle of superposition of strata, those in the lower strata will also be older than those in the upper strata. As the strata containing the same type of fossil were deposited at the same time, if we know the relative age of the fossil, we can know the age of the stratum that contains it, even if it is elsewhere. By Kurt Rosenkrantz [CC BY-SA 3.0], via Wikimedia Commons Principle of superposition of events A geological process that affects some materials is always after them, and before the materials that it does not affect and the processes that affect it. For example, if a rock appears folded, the rock will be older than the fold. Or if it is a short stratum to another, the one that appears cut is the oldest. Principle of uniformism or uniformitarianism The uniformism or uniformitarianism is the principle according to which the natural processes that acted in the past are the same that act in the present and with the same intensity. This principle states that geological processes (erosion, plate movement, etc.) have remained uniform throughout geological time. Principle of actualism The actualismo can be summed up with the phrase "the present is the key to the past". It means that the processes that take place today (magmatism, sedimentation, earthquakes, etc.) are the same that have happened throughout the history of the Earth. Thus, by studying the present we can obtain information about what happened in the past and get an idea of the changes that have occurred on Earth since its formation. The ripples in the sand on the beach, current and fossil, are similar . Interactive activity: Biological or geological processes?. Interactive activity: Geological principles. Interactive activity: More geological principles. Animation: How to make geological sections from geological maps. Licensed under the Creative Commons Attribution Share Alike License 4.0 « Previous \| Next » You can ask, comment, contribute, get in touch with other users in the forum of this course. This course is translated from https://biologia-geologia.com/BG4/
Legal warning	Blog	Download	Contact

Follow us if it has been useful to you biologia-geologia.com. Biology and Geology teaching materials for Compulsory Secondary Education (ESO) and Baccalaureate students.

BIOLOGÍA - GEOLOGÍA . COM