Radiometric dating, geologic time, and the age of the Earth; a reply to "scientific" creationism

Radiometric dating of rocks and minerals to constrain the age of the Earth, timing of geological events and paleobiological histories has its roots in the works of nuclear physicists of the early Nineteenth Century during the period of discovery of radioactivity and investigations into the nature of the atom. The intervening years since have seen great progress in using the long-lived radioactive elements to constrain the origin and evolution of the Earth and to place the rock and fossil record into a consistent, numerically quantifiable temporal framework.U-Th-Pb and40Ar/39Ar dating methods have emerged as the primary tools for calibrating most of Earth history. It is important for all geoscientists to appreciate the physical basis underlying these methods and to have the ability to evaluate dates by means of currently accepted practices of data presentation. This introduction, along with the accompanying chapters, is intended to help the consumers of radiometric dates to understand better the uses and limitations of radiometric dating methods in an effort to tailor methods and techniques to address specific geochronologic needs, including calibration of the geologic time scale.The ultimate goal of a fully calibrated rock record remains an on-going endeavor. The 2004 ICS geologic time scale is the latest compilation of those efforts. The numerical age calibration is constrained by only 213 radiometric dates, the vast majority of which are U-Pb and40Ar/39Ar dates. Radiometric age control is not evenly distributed through geologic time. There are virtually no radiometric dates in the late Cenozoic where magnetostratigraphy and cyclostratigraphic methods are more precise and applicable. Radiometric dating efforts are concentrated on biostratigraphically important segments of the rock record such as the Permian-Triassic and Cretaceous-Paleocene boundary events, and this is reflected in high-precision calibration of these boundaries. Large segments of geologic time, however, are constrained by either a few radiometric dates per chronostratigraphic unit (most of the Paleozoic) or none at all (Upper Triassic). The current status of radiometric age control on the rock record largely reflects real, underlying scientific issues in biostratigraphy and geochronology, and thus can help point the way to fruitful lines of collaboration between paleontologists, stratigraphers, and geochronologists.

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Song of the Earth

10.1093/oso/9780197502464.001.0001 ◽

2021 ◽

Author(s):

Elisabeth Ervin-Blankenheim

Keyword(s):

Climate Change ◽

Plate Tectonics ◽

Life Forms ◽

Historical Maps ◽

Mountain Building ◽

Species Extinction ◽

Geologic Time ◽

The Earth ◽

The Relationship

This book is a scientific, historical, and philosophical narrative for general readers that explores the relationship between humans and the Earth and the geologic principles of time, plate tectonics, and change in life forms. Illustrated with striking historical maps, figures, and pictures, this comprehensive work can be read as a thrilling biography of the Earth itself, including narrative sections on the lives of pioneering geologists; the reality and sublimity of geologic time; the birth, destruction, and rebirth of the planet and its atmosphere over repeated cycles spanning some 4-plus billion years; the science underlying both mountain building and oceanic evolution; the influence of climate change and species extinction on the development of the Earth; and the interplay between not only how Earth has influenced life but how life, in turn, has distinctly shaped our planet.

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LEONARDO DA VINCI’S AND NICOLAUS STENO’S GEOLOGY

Earth Sciences History ◽

10.17704/1944-6187-40.2.293 ◽

2021 ◽

Vol 40 (2) ◽

pp. 293-331

Author(s):

GIAN BATTISTA VAI

Keyword(s):

Comparative Evaluation ◽

Geological History ◽

Basic Principles ◽

Founding Fathers ◽

Angular Unconformity ◽

Geologic Time ◽

The Earth ◽

Relative Chronology ◽

History Of ◽

Do So

Anniversaries for the two founding fathers of geology occurring in the same year prompted a comparative evaluation of how the two contributed to establishing the basic principles of the discipline. To do so, passages from their publications, codices and manuscripts have been quoted directly. The Stenonian principles (‘original horizontality’, ‘original continuity’, and ‘superposition of individual strata’) are present in Leonardo’s notebooks amazingly formulated, using similar wording when studying the same area more than 150 years earlier. Also, Stenonian priority in naming and explaining geological concepts and processes (e.g., faulting, folding, angular unconformity, relative chronology) are mirrored in Leonardo’s writings and pictorial works. While Steno enjoys priority in stepwise restoration of the geological history of a given region, Leonardo was the first to construct a 3D geological profile representation and geomorphologic maps. Lastly, the paper focuses on diverging stances of the two savants about the Noachian Deluge and the age of the Earth. Already 500 years ago, Leonardo had solved the question of marine fossil remains of organic origin found in the mountains implying the possibility of deep geologic time in a statement of ‘eternalism’. 350 years ago, Steno solved the same question in a different way in which he retained a basic role for the Deluge and assumed a short age for the Earth by focusing mainly on short-lived sedimentary and geomorphologic processes.

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The Earth through geologic time

Physical Science in the Modern World ◽

10.1016/b978-0-12-472260-6.50010-0 ◽

1974 ◽

pp. 150-173

Author(s):

JERRY B. MARION

Keyword(s):

Geologic Time ◽

The Earth

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The Biography of the Earth

10.1093/oso/9780197502464.003.0009 ◽

2021 ◽

pp. 163-180

Author(s):

Elisabeth Ervin-Blankenheim

Keyword(s):

Early Life ◽

Plate Tectonics ◽

Life Forms ◽

Snowball Earth ◽

The Moon ◽

Geologic Time ◽

Earth Systems ◽

Organic Life ◽

The Earth ◽

Geologic Record

The way the planet has changed through geologic time, and life on it, the account of the Earth, is the topic of this and the next three chapters, starting in this chapter with the Precambrian Supereon. The overarching principles of geologic time, plate tectonics, and evolution worked dynamically to create the biography of the planet. This chapter traces back to the recesses of the geologic record and early Earth, from its birth and the formation of the Moon through seven-eighths of its existence, a huge span of time. Early life forms emerged during this supereon in the Archean Eon and had a profound influence on other Earth systems. Life interacted and changed the chemistry of the atmosphere through photosynthesis, so much so that the changes are thought to have sent planetary systems over an edge into multiple “Snowball Earth” episodes when most of the planet froze over. In addition to the beginning of organic life and climate, the emergence and configuration of the continents during the Precambrian are covered. Events of this supereon set the stage for the burgeoning of life forms in the next eon, the Phanerozoic.

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The History of the Earth in the hallways

10.5194/egusphere-egu2020-22046 ◽

2020 ◽

Author(s):

Paloma Ramírez Vongrejova ◽

María José Massé Rodríguez

Keyword(s):

School Students ◽

Learning Groups ◽

Geologic Time ◽

The Earth ◽

Experience Teaching ◽

Widespread Agreement ◽

Geologic Time Scale ◽

History Of ◽

The Subject ◽

Research Period

There is widespread agreement among my fellow colleagues who teach Geology that the History of our planet is a tough topic for teenagers. Unfortunately, not only is the subject considered boring but also useless by the majority of our school students.Our experience teaching these contents in a traditional way has shown us that pupils vaguely remember anything. In order to give a different approach to this issue and, therefore, to promote meaningful learning, we have designed a project where students must be fully engaged.First, the class was organized in cooperative learning groups, so they had to collaborate to complete the task. Then, they started the research period using laptop computers available in the school. Students now dealt with specific vocabulary such as the geologic time scale terms but also a variety of events that occurred from the very first moments, from the formation of the Earth itself to the development of the big reptiles that have always fascinated children and adults, especially their dramatic extinction. Once the topic was developed in detail, they were required to make a poster on scale with the information collected. It was undeniable that pictures or photographs must cover most of the poster as long as short sentences describing both biological and geological phenomena. What we were also concerned about their learning was to improve their creativity. Because of this, they were encouraged to make their own drawings.Students really liked the activity, built stronger relationships between them and the final products were so amazing that were exhibited in the walls of the hallways outside their classroom.All these events have been recorded in the rocks so geologists could unfold part of the mysteries of our History. Our teenagers discovered them an represented them for us to enjoy.

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Does topography matter for rocky exoplanets?

10.5194/epsc2020-914 ◽

2020 ◽

Author(s):

Claire Marie Guimond ◽

Oliver Shorttle ◽

John F. Rudge

Keyword(s):

Solar System ◽

Building Materials ◽

Silicate Weathering ◽

Earth System ◽

Dynamic Topography ◽

Geologic Time ◽

Scaling Relationships ◽

The Earth ◽

Crucial Component ◽

Rocky Planets

Topography is a crucial component of the Earth system: having rock exposed to the atmosphere lets surface temperatures self-regulate via silicate weathering, for example. However, there are limits to a lithosphere&#8217;s capacity to support mountains or valleys over geologic time. We see in our solar system that the range in a body&#8217;s elevations tends to decrease with increasing planet mass. These trends, inherent to planetary building materials, are modelled using well-studied concepts from geodynamics. As a first step, we predict feasible thermal evolutions and dynamic topography scaling relationships for rocky planets, eventually gearing to ask how massive a planet can be and still likely maintain subaerial land.

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Geologic Time

10.1093/oso/9780197502464.003.0004 ◽

2021 ◽

pp. 47-68

Author(s):

Elisabeth Ervin-Blankenheim

Keyword(s):

Time Scale ◽

Sedimentation Rates ◽

Charles Lyell ◽

Geologic Time ◽

The Bible ◽

The Earth ◽

Time To Build ◽

Over Time

The time scale of geology—the first overarching precept in geology—and its development are the focus of this chapter. How did geologists determine the great age of the Earth through the spatial nature of geologic units and changes in fossils over time? There was no guidebook to the process of unraveling the Earth’s biography, and the discoveries proceeded step by step using observation and the development of hypotheses. Scientists such as Abraham Werner established principles to place rocks in order relative to one another, providing the beginning of understanding strata, their composition, sources, and life within them. Early estimates of the age of the Earth were on the order of thousands of years, carefully calculated based on the generations in the Bible. However, geologists such as James Hutton and Charles Lyell realized that the probable age of the Earth was much greater by examining the time it would take for processes, like sedimentation rates for a layer of sand or mud to be deposited to occur. From these observations, they deduced it would take orders of magnitude more time to build up great masses of rock layers, and the time scale of geology was extended millions of years.

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"Geologic Time" As Calculated By C. D. Walcott

Earth Sciences History ◽

10.17704/eshi.8.2.j68n416801537r44 ◽

1989 ◽

Vol 8 (2) ◽

pp. 150-158 ◽

Cited By ~ 1

Author(s):

Ellis Yochelson

Keyword(s):

North America ◽

Radiometric Dating ◽

Time Interval ◽

Western North America ◽

Geologic Time ◽

Paleozoic Rock ◽

Ocean Salinity ◽

Rock Column ◽

Paleozoic Rocks ◽

Paleozoic Carbonates

In 1893, Walcott contributed to the debate on the length of geologic time. He approached the problem by calculating average thickness of the Paleozoic rock column in the west and dividing by rates of erosion and by rates of deposition to arrive at a time interval. Although he concentrated on the Cordilleran area, Walcott produced a general paleogeographic scheme for the Paleozoic of North America. He was quite clear in differentiating between chemical and mechanical deposits, and devoted most of his attention to the Paleozoic carbonates. Walcott chose western North America as the source for data, in part because of the long sections and in part because of the large amount of limestone relative to sandstone and shale. Throughout the discussion he included pertinent comments on such subjects as size of source areas and relative speed of deposition; he was familiar with many of the issues that occupy present-day sedimentologists. After considering various aspects of the issue, Walcott estimated 17,500,000 years for the duration of the Paleozoic. Walcott also derived a Paleozoic: Mesozoic: Cenozoic ratio of 12: 5: 2, the same ratio obtained today from radiometric dates. He estimated that the Algonkian was as long as Paleozoic and guessed 10,000,000 years for the duration of the Archean. The greatest flaws in his chain of logic were assumption of an erosion rate of 1 foot in 200 years and assumption that deposition of limestone was more or less continuous. Had he chosen 1 foot per 3,000 years, one of his other two calculations, he would have been close to present-day age figures. Perhaps it was the episodic, rather than the average, nature of sedimentation that was the pitfall. Nevertheless, Walcott's estimates of thicknesses of western Paleozoic rocks and his resulting calculations were the most detailed made on erosion/sedimentation rates to indicate the length of geologic time. His study was published in three journals, plus other outlets, and it may have been the most widely distributed paper of the decade. It was little cited, perhaps because within several years the debate on age shifted to use of ocean salinity as a potentially more precise calender. That approach in turn ultimately succumbed to the new concept of radiometric dating.

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Picturing Evolution through Geologic Time

The American Biology Teacher ◽

10.1525/abt.2016.78.2.137 ◽

2016 ◽

Vol 78 (2) ◽

pp. 137-140

Author(s):

Lloyd H. Barrow

Keyword(s):

Visual Representation ◽

Biology Students ◽

Geologic Time ◽

The Earth

The purpose of this activity is to provide precollege biology students a visual representation of evolution. Unfortunately, many resources begin with the start of life, which ignores the fact that the Earth is 4.6 billion years old. This model uses adding-machine tape to sequence events. Representation of major evolutionary and geologic events helps students visualize macroevolution.

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