Rocks have always played a significant role in unraveling the mysteries of our planet’s history. They hold within them a story that stretches back millions, even billions, of years. Understanding the vast span of geologic time is essential for comprehending the Earth’s evolution, from the formation of its earliest rocks to the complex geological processes that continue to shape our world today.
In this article, we delve into the fascinating realm of geologic time to explore the age-old question, “How old do rocks live?” As we peel back the layers of time, we’ll examine the methods scientists use to estimate the age of rocks and unlock the secrets they hold. We’ll delve into the concept of deep time and the mind-boggling scale of Earth’s history, where billions of years become mere intervals within the tapestry of geological events. Get ready to embark on a journey through the eons as we seek to unravel the mysteries that lie hidden within the rocks beneath our feet.
The concept of rock age
A. Definition of rock age
The concept of rock age refers to the length of time that a rock has existed on Earth. It is a crucial aspect of geologic time and provides valuable insights into the Earth’s history. Rock age is measured in millions, billions, or even trillions of years, and understanding it is fundamental in unraveling the mysteries of geologic time.
B. How rock age is determined
Determining the age of a rock involves various scientific methods and techniques. One of the most common and reliable methods is radiometric dating, which relies on the principle that certain radioactive elements decay at a known rate over time. By measuring the ratio of parent and daughter isotopes in a rock sample, scientists can calculate its age. This technique has proven to be highly accurate and has significantly contributed to our understanding of geologic time.
Another method used to determine rock age is relative dating. This approach relies on the principle of superposition, which states that in undisturbed rock layers, the younger layers are deposited on top of older layers. By examining the order of rock layers and the fossils they contain, scientists can deduce the relative age of different rocks.
Both absolute and relative dating methods are essential in determining the age of rocks. They provide complementary information and help create a more comprehensive picture of Earth’s history. This knowledge is crucial for various fields of study, including paleontology, climate science, and environmental studies.
Understanding rocks as records of Earth’s history
A. Rocks as storytellers
Rocks are like archives that store information about the Earth’s past. By studying rocks, scientists can reconstruct ancient environments, understand geological processes, and even uncover evidence of past life forms. Each layer of rock represents a snapshot of a particular time in Earth’s history and provides valuable clues about the conditions that existed at that time.
B. Layers of sedimentary rocks
Sedimentary rocks, in particular, are excellent records of Earth’s history. They are formed through the accumulation and cementation of sediment, such as sand, mud, or organic material, over long periods of time. As sediment is transported and deposited, it forms distinct layers or strata. By examining the characteristics of these layers, scientists can decipher the ancient environments in which they formed and gain insights into past climates, ecosystems, and geological events.
Understanding rocks as records of Earth’s history is essential for reconstructing past environments, predicting future geological changes, and making informed decisions regarding environmental conservation and resource management. It allows us to appreciate the immense timescales involved in geologic processes and how they have shaped the world we live in today.
Understanding rocks as records of Earth’s history
A. Rocks as storytellers
Rocks, as the oldest materials on Earth, hold a vast amount of information about the planet’s history. They serve as silent storytellers, preserving evidence of past events and providing valuable insights into the Earth’s geological past. By studying rocks, scientists can unravel the mysteries of geologic time and gain a deeper understanding of how the Earth has evolved over billions of years.
B. Layers of sedimentary rocks
One of the key aspects of understanding rocks as records of Earth’s history lies in studying the layers of sedimentary rocks. Sedimentary rocks are formed by the accumulation and compression of sediments, such as sand, clay, and organic matter, over long periods of time. Each layer represents a distinct time period, recording the different environmental conditions and processes that occurred during its formation.
The study of sedimentary rock layers, known as stratigraphy, allows geologists to establish a relative chronology of events. By examining the sequence of layers and the fossils they contain, scientists can deduce the order in which different rocks formed. This information helps establish the relative ages of rock formations and provides a framework for understanding the Earth’s history.
The layers of sedimentary rocks also hold clues about past climate and environmental conditions. Fossils found within these layers provide evidence of ancient life forms and can indicate the types of environments that existed at the time of their formation. For example, the presence of marine fossils in certain layers suggests that the area was once covered by a shallow sea.
Moreover, sedimentary rocks can also reveal information about the Earth’s tectonic activity, such as the shifting of continents and the formation of mountain ranges. The deposition of sediments along coastlines and the erosion of mountains leave distinct patterns in the layers, allowing geologists to reconstruct past geological events.
Understanding the stories hidden within sedimentary rocks is crucial for unraveling the mysteries of geologic time. By carefully analyzing these layers, scientists can piece together the puzzle of Earth’s history, providing valuable insights into how our planet has changed over time and how it may continue to evolve in the future.
IUnraveling the mysteries of geologic time
A. Studying rock layers and fossils
Understanding the mysteries of geologic time requires a comprehensive study of rock layers and the fossils contained within them. Rocks are like the storytellers of Earth’s history, recording events that occurred millions and even billions of years ago. By examining the rock layers and the fossils they contain, scientists can piece together the events that shaped our planet.
Rock layers, also known as strata, are formed through various processes such as deposition, erosion, and volcanic activity. Each layer can provide valuable information about the conditions under which it was formed. By studying the characteristics of different rock layers, scientists can determine the relative order in which they were deposited. This principle, known as relative dating, allows them to establish a timeline and understand the sequence of events that occurred over geologic time.
Fossils play a crucial role in deciphering the story of rock layers. Fossils are the remains or traces of ancient organisms preserved within rocks. They provide a glimpse into the past, revealing the types of organisms that inhabited the Earth millions of years ago. By examining the fossils found in different rock layers, scientists can determine the age of those layers and infer the environmental conditions that existed at the time of their formation.
B. Relative dating techniques
In addition to studying rock layers and fossils, scientists employ relative dating techniques to unravel the mysteries of geologic time. Relative dating relies on the principle of superposition, which states that in undisturbed rock layers, the youngest rocks are found at the top, while the oldest rocks are found at the bottom.
One common relative dating technique is known as stratigraphy. This involves analyzing the sequence and arrangement of rock layers to determine their relative ages. By observing the characteristics of different layers, such as their composition, color, and texture, scientists can deduce their relative positions in the geologic timeline.
Another relative dating technique is paleontological correlation. This method involves comparing the fossils found in different rock layers to establish their relative ages. Certain fossils are known to have existed only within specific time periods. By identifying these fossils in various rock layers, scientists can correlate the ages of those layers and create a cohesive timeline of Earth’s history.
While relative dating provides valuable insights into geologic time, it does not provide precise numerical ages for rocks and events. To obtain more accurate ages, scientists turn to absolute dating methods, which will be explored in the next section.
Overall, the study of rock layers and fossils, combined with the application of relative dating techniques, allows scientists to unravel the mysteries of geologic time. By piecing together this intricate puzzle, they gain a deeper understanding of Earth’s history and its influence on the present and future.
## Absolute dating methods
### A. Radiometric dating
Radiometric dating is a powerful tool used by geologists to determine the absolute age of rocks and minerals. This method relies on the principles of radioactive decay, which occur at a predictable rate over time. By measuring the ratio of parent isotopes to daughter isotopes in a sample, scientists can calculate how long it has been since the rock or mineral formed.
One commonly used radiometric dating technique is uranium-lead dating. Uranium naturally decays into lead over time, with a known half-life of about 4.5 billion years. By measuring the ratio of uranium to lead in a sample, geologists can determine its age. This method is particularly useful for dating rocks that are billions of years old, such as those found in the Earth’s crust.
Other radiometric dating methods include potassium-argon dating, which is used to date volcanic rocks, and carbon-14 dating, which is used to date organic materials up to about 50,000 years old. Each method is based on the decay of specific isotopes and has its own set of limitations and applications.
Radiometric dating provides geologists with a quantitative measure of geologic time, allowing them to establish precise ages for rocks and minerals. This information is crucial for understanding Earth’s history and the processes that have shaped the planet over billions of years.
### B. Half-life and decay
In radiometric dating, the concept of half-life is essential. The half-life of a radioactive isotope is the time it takes for half of the original parent atoms to decay into the daughter atoms. This value is constant for each isotope and allows scientists to calculate the age of a sample.
For example, if the half-life of uranium-238 is 4.5 billion years, after 4.5 billion years, half of the original uranium atoms will have decayed into lead atoms. After another 4.5 billion years, half of the remaining uranium atoms will have decayed, and so on.
By measuring the ratio of parent to daughter atoms in a sample and knowing the half-life of the isotope, scientists can determine the number of half-lives that have occurred and calculate the sample’s age. The longer the half-life, the older the sample can be reliably dated. Shorter half-lives are used to date younger materials.
Decay is a random process, meaning that it is impossible to predict when any individual atom will decay. However, by analyzing a large number of atoms, scientists can make accurate predictions about the overall rate of decay.
Understanding the concept of half-life and decay is fundamental to interpreting radiometric dating results and unraveling the mysteries of geologic time. It provides an objective and quantitative approach to determining rock ages, helping to piece together Earth’s history and shed light on the processes that have shaped our planet over billions of years.
Oldest rocks on Earth
The search for the oldest rocks on Earth has long fascinated scientists, as these ancient formations hold valuable clues about the early history of our planet. Determining the age of these rocks is crucial for understanding Earth’s formation and the evolution of life.
A. The search for the oldest rocks
Geologists have conducted extensive research and expeditions to discover the oldest rocks on Earth. These rocks are often found in remote locations, such as the Canadian Shield, Western Greenland, Western Australia, and South Africa. These regions offer unique geological characteristics that make them prime locations for finding ancient rock formations.
One of the main challenges in finding the oldest rocks is that they have been subjected to intense heat, pressure, and erosion over billions of years, thereby altering their original composition and structure. However, there are certain types of rocks that have proved exceptionally useful in dating the past.
B. Zircon crystals as a key to dating the past
Zircon crystals, a mineral commonly found in granite and other igneous rocks, have become a crucial tool for dating the age of rocks. Zircons contain trace amounts of radioactive isotopes, such as uranium and thorium, which decay over time at a predictable rate. By analyzing the ratio of parent isotopes to daughter isotopes in zircons, scientists can estimate the age of the rock formation in which they are found.
Researchers have utilized advanced techniques, such as uranium-lead dating, to determine the age of ancient zircons. These studies have revealed some remarkable findings, including the existence of rocks dating back 4.4 billion years, just a few hundred million years after the formation of the Earth itself.
The discovery of these ancient rocks provides valuable insights into the early conditions of Earth, including the formation of the oceans, the emergence of life, and the evolution of the atmosphere. Furthermore, they help establish benchmarks for events in the geological timescale and shed light on the processes that have shaped our planet over billions of years.
The Role of Paleontology in Understanding Rock Age
Fossil Evidence as Time Indicators
Paleontology, the study of fossils, plays a pivotal role in understanding the age of rocks and unraveling the mysteries of geologic time. Fossils are the preserved remains or traces of ancient organisms that are found within rocks. These remnants provide invaluable clues about the organisms that lived in the past, as well as the environments in which they thrived. By examining the fossils present in rocks, scientists can gain insights into the age of those rocks and the geologic events that shaped Earth’s history.
Fossils serve as time indicators because they provide evidence of the organisms that inhabited the Earth at specific points in time. Different organisms existed during different periods, and these organisms can be used to date the rocks in which their remains are found. For example, if a certain type of fossil is known to have lived during the Cretaceous Period, the rock containing that fossil can be dated to that period. By studying the distribution and characteristics of fossils, paleontologists can establish the relative ages of rocks and create a chronological sequence of Earth’s history.
Fossil Types and Their Significance
Various types of fossils exist, and each type has its own significance in understanding the age of rocks. Body fossils are the remains or impressions of the actual organisms, such as bones, teeth, shells, or imprints of soft tissues. These fossils provide direct evidence of the organisms that lived in the past and are often used to identify and classify ancient species.
Trace fossils, on the other hand, are indirect evidence of organisms and their activities. They include tracks, burrows, and feces left behind by ancient organisms. These fossils reveal the behavior and ecological interactions of organisms, providing insights into past ecosystems and environmental conditions.
Microfossils are another type of fossil that are tiny in size and require microscopic examination. These include microscopic plants, animals, and bacteria that can be found in sedimentary rocks. Microfossils are particularly useful in dating rocks and determining ancient climates, as they provide information about the ecological niches and environmental conditions of the past.
By identifying and analyzing these different types of fossils, paleontologists can piece together the story of Earth’s history and contribute to our understanding of rock age and geologic time. Fossils serve as invaluable time capsules, offering glimpses into the ancient past and helping us unravel the mysteries of the world around us.
Geological formations and their ages
A. Identifying and dating different formations
Geological formations are key to understanding the history of the Earth. These formations provide information about past environments, climate, and even the presence of ancient life forms. Identifying and accurately dating these formations is crucial for unraveling the mysteries of geologic time.
Geologists use various methods to identify different formations. One of the primary techniques is stratigraphy, which involves studying the layers or strata of rocks. Different formations have distinct characteristics such as composition, color, and fossil content, which aid in their identification.
Dating these formations is essential in determining their ages and placing them within the geological timescale. Geologists employ both relative and absolute dating techniques for this purpose.
B. The role of strata in determining age
Strata play a vital role in determining the relative age of geological formations. The Law of Superposition states that in a series of undisturbed rock layers, the youngest rocks are on top, and the oldest rocks are at the bottom. Therefore, by examining the order of the strata, geologists can determine which formations are older or younger than others.
However, it is important to note that the Law of Superposition only provides relative ages and does not give specific numerical dates. To assign precise ages to formations, geologists need to rely on absolute dating methods.
Combining the principles of stratigraphy with absolute dating techniques such as radiometric dating allows geologists to accurately determine the ages of different formations. This knowledge is crucial for constructing a detailed geological timescale and understanding the sequence of events that have shaped the Earth over billions of years.
By analyzing the layers of sedimentary rocks in different formations and studying the fossils contained within them, geologists can also gain insights into ancient environments and the evolution of life on Earth. Fossils provide a record of past organisms and their distribution, helping geologists piece together the puzzle of geologic time.
Understanding the age of geological formations is not only essential for geological studies but also plays a significant role in environmental studies. By examining the past, scientists can better predict and understand future changes in climate, ecosystems, and natural resources.
In conclusion, geological formations are fundamental to unraveling the mysteries of geologic time. Identifying and dating these formations using stratigraphy and absolute dating methods allows geologists to create a comprehensive timeline of Earth’s history, providing insights into past environments, climate, and the evolution of life. This knowledge is invaluable for both geological and environmental studies.
The dating game: Challenges in determining rock ages
A. Disruptive events and their impact on age estimation
Determining the ages of rocks is a complex task, as there are several challenges and disruptive events that can impact age estimation. These events can often complicate the dating process and lead to inaccurate results.
One major disruptive event that affects age estimation is known as “metamorphism.” Metamorphism occurs when rocks are subjected to high temperature and pressure, causing significant changes in their mineral composition and structure. This can reset the isotopic clocks used in radiometric dating methods, making it difficult to determine the true age of the rocks.
Another disruptive event is known as “tectonic activity.” Tectonic plates are constantly moving and colliding with each other, causing major deformation and displacement of rock layers. This can result in mixing and overturning of different rock units, making it challenging to establish the correct sequence of events and accurately determine the ages of the rocks.
Furthermore, gap sediments, also known as unconformities, pose another challenge in age determination. Unconformities occur when there is a period of erosion or non-deposition, causing a gap or missing section in the rock record. This can make it difficult to establish continuous sequences of rock layers, making it hard to determine the relative ages of the rocks in these regions.
B. Limitations of dating techniques
While there are several dating techniques available, it is important to recognize their limitations. Each dating method has its own range of applicability and precision, and it is crucial to use the appropriate method depending on the age and type of rocks being studied.
For example, radiometric dating relies on the decay of radioactive isotopes in rocks and minerals. However, this method is only applicable to rocks that contain certain types of isotopes with long half-lives. Additionally, contamination and loss of parent or daughter isotopes can occur over time, further complicating the dating process.
Another limitation is the availability and quality of samples. In some cases, it may be difficult to obtain suitable samples for dating, especially if the rocks are deeply buried or inaccessible. Additionally, the accuracy of dating results can be affected by sample selection and preparation techniques, as well as potential contamination from the environment.
Furthermore, dating methods often provide a range of possible ages rather than a precise value. This is due to uncertainties associated with the measurements and assumptions made during the dating process. It is important to consider these uncertainties and use statistical methods to determine the most probable age range for a given rock sample.
In conclusion, determining the ages of rocks is a challenging task due to disruptive events and the limitations of dating techniques. Despite these challenges, scientists continue to develop new methods and refine existing ones to improve the accuracy and precision of age estimations. This ongoing research plays a crucial role in unraveling the mysteries of geologic time and deepening our understanding of Earth’s history.
The Geological Timescale
A. Overview of the timescale
The geological timescale provides a framework for understanding the vast expanse of Earth’s history. It is divided into various units that reflect different periods of time, ranging from billions of years to more recent eras. The timescale helps scientists to organize and study the events and changes that have occurred throughout Earth’s history. It serves as a chronological record of geological events.
The timescale is divided into several hierarchical levels. The largest divisions are eons, followed by eras, periods, epochs, and ages. Each unit represents a significant and distinct period characterized by specific geological and biological events. The boundaries between these units are often marked by significant geological or paleontological events.
B. Major events and epochs in Earth’s history
The geological timescale is marked by several major events and epochs that have shaped the Earth’s history. For example, the Paleozoic era, which spans from around 541 to 252 million years ago, is known for the explosion of diversity in marine life, the colonization of land by plants and animals, and the formation of the supercontinent Pangaea.
The Mesozoic era, lasting from about 252 to 66 million years ago, witnessed the rise and dominance of dinosaurs, the breakup of Pangaea, and the emergence of mammals and flowering plants. It also witnessed the catastrophic event that led to the extinction of dinosaurs, opening the way for the evolution of mammals.
The Cenozoic era, which started around 66 million years ago and continues to the present day, is characterized by the diversification and proliferation of mammals, the evolution of humans, and the development of our modern climate and ecosystems.
The geological timescale also includes epochs such as the Pleistocene, which began around 2.6 million years ago and is marked by fluctuating climates and the appearance and disappearance of ice ages. The Holocene epoch, which started around 11,700 years ago, represents the present era of relatively stable and warm climate that has allowed human civilization to flourish.
Understanding the major events and epochs in Earth’s history is crucial for gaining insight into the processes and changes that have shaped our planet. It provides a context for studying past and present geological, biological, and environmental phenomena, which has implications for predicting and managing future changes. The geological timescale serves as a valuable tool for scientists to unravel the mysteries of geologic time and gain a deeper understanding of Earth’s complex history.
Ancient rocks and climate change
A. Understanding past climate through rock records
Ancient rocks hold valuable information about Earth’s climate history. By examining the composition and structure of rocks, scientists can reconstruct past climates and gain insights into how the Earth’s climate system has changed over time. Rocks provide a window into the past, offering clues about temperature, precipitation, and other environmental conditions.
One way in which rocks help us understand past climate is through the study of isotopes. Isotopes are variations of an element with different numbers of neutrons in the nucleus. Certain isotopes, such as oxygen-18 and carbon-13, are particularly useful in climate reconstructions. These isotopes can be analyzed in ancient rocks to determine past temperatures and atmospheric conditions.
For example, the ratio of oxygen-18 to oxygen-16 in rocks can indicate the temperature at which the rock formed. This information allows scientists to infer past climate conditions and track changes over time. Similarly, the ratio of carbon-13 to carbon-12 in rocks can provide insights into past levels of atmospheric carbon dioxide, a key greenhouse gas.
B. Proxy records and their role in climate studies
Proxy records are indirect measurements or indicators of past climate conditions. Rocks serve as important proxy records because they preserve evidence of past climates through various means. For instance, tree rings in ancient petrified trees can indicate annual variations in temperature and precipitation, providing a record of past climate conditions.
Ice cores are another valuable proxy record. By drilling deep into glaciers or ice sheets, scientists can extract long cylinders of ice that contain trapped air bubbles from thousands of years ago. The composition of these air bubbles, including levels of greenhouse gases like carbon dioxide, provides valuable information about past climates.
Rocks can also preserve other indicators of climate, such as the presence of certain fossils or the types of minerals present. By studying these proxies, scientists can piece together a picture of past climate patterns, including the timing and extent of ice ages, periods of global warming, and shifts in ocean currents.
Understanding ancient rocks and their relationship to climate change is crucial for projecting future climate scenarios. By studying past climate variations, scientists can develop models to predict how Earth’s climate may respond to future changes. This knowledge is essential for making informed decisions about mitigating and adapting to climate change.
In conclusion, ancient rocks serve as invaluable records of Earth’s climate history. Through the analysis of isotopes, proxy records, and other indicators, scientists can reconstruct past climates and gain insights into how the Earth’s climate system has evolved over millions of years. This knowledge is essential for understanding current climate change patterns and predicting future climate scenarios. By unraveling the mysteries of geologic time, we can better appreciate the intricate relationship between rocks, climate, and the environment.
Longevity of rocks and their preservation
A. Factors influencing rock longevity
In order to understand the longevity of rocks and how they can survive for billions of years without significant alteration, it is important to consider the various factors that influence their preservation. One key factor is the composition of the rock itself. Rocks that are composed of more resistant minerals, such as quartz or feldspar, are more likely to withstand the effects of erosion and weathering. In contrast, rocks made of softer minerals like clay or gypsum are more easily weathered and broken down over time.
Another factor that influences rock longevity is the environment in which the rocks are located. For example, rocks that are buried deep underground are protected from the processes of erosion and weathering that occur at the Earth’s surface. This is why rocks found in mountain ranges or other areas of active uplift are often well-preserved. On the other hand, rocks exposed at the surface are more vulnerable to these processes and are more likely to be eroded or weathered away.
The presence of protective layers can also contribute to the longevity of rocks. For example, layers of sediment or volcanic ash can act as a barrier, shielding underlying rocks from the effects of erosion. Additionally, rocks that are covered by ice, such as those found in glaciers or polar regions, are also preserved due to the protective nature of the ice cover.
B. How rocks survive billions of years without significant alteration
One of the main reasons rocks can survive for billions of years without significant alteration is due to the slow processes of erosion and weathering. Although these processes occur constantly, they often occur at a gradual pace, preserving rocks over long periods of time. Additionally, factors such as the composition of the rock and the environmental conditions it is exposed to can also contribute to its preservation.
Another factor that helps rocks survive without significant alteration is the process of lithification. Lithification refers to the transformation of loose sediment into solid rock. This process typically involves the compaction and cementation of sediment, which helps to bind the particles together and create a more durable rock.
Additionally, rocks can be protected from alteration through burial and the deposition of sediment. When rocks are buried deep underground, the pressure from overlying layers of sediment or rock can help to preserve them. This pressure, combined with other factors such as temperature and the absence of oxygen, can inhibit the chemical reactions that would lead to alteration.
Furthermore, certain geological processes can contribute to the preservation of rocks. For example, the process of metamorphism can transform existing rocks without completely destroying them. Instead, metamorphism causes changes in the mineral composition and structure of the rocks, while still preserving their overall integrity.
In conclusion, the longevity of rocks and their preservation over billions of years can be attributed to a combination of factors. The composition of the rock, the environment in which it is located, the presence of protective layers, as well as slow processes of erosion and weathering all play a role in preserving rocks and allowing them to serve as records of Earth’s history. Understanding these factors is crucial for unraveling the mysteries of geologic time and gaining insights into our planet’s past.
Conclusion
A. Importance of unraveling the mysteries of geologic time
Geologic time is a fundamental concept in understanding Earth’s history. By unraveling the mysteries of geologic time, scientists gain valuable insights into the processes that have shaped our planet over billions of years. Understanding geologic time allows us to make informed decisions about resource management, environmental conservation, and mitigating the impacts of hazards such as earthquakes and volcanic eruptions.
B. The relevance of rock age in geological and environmental studies
The age of rocks plays a crucial role in various geological and environmental studies. Through the examination of rock layers, scientists can reconstruct past climates, track the evolution of life forms, and identify key events in Earth’s history. This information is vital for predicting future changes in our environment and understanding the long-term consequences of human activities.
Knowing the age of rocks is also essential for resource exploration. By dating different formations, geologists can identify potential deposits of minerals, oil, and gas. This knowledge is crucial for sustainable resource management and ensuring a reliable energy supply for future generations.
Furthermore, understanding the age of rocks helps us make accurate geological maps and predict the behavior of rock formations in engineering projects. It provides critical information for the construction of infrastructure such as roads, bridges, and buildings, ensuring their stability and long-term resilience.
In conclusion, unraveling the mysteries of geologic time is of paramount importance for a wide range of scientific disciplines. The study of rock age enables us to piece together Earth’s history, comprehend the forces that have shaped our planet, and make educated decisions to protect and sustain our environment and resources. The ongoing advancements in dating techniques and the innovative methods of studying ancient rocks and fossils will continue to expand our knowledge of geologic time, contributing to a better understanding of our world and its future.