Soils of the Past

An Introduction to Paleopedology

Gregory J. Retallack

• Publisher: Wiley-Blackwell
• Year: 2019
• ISBN:
  9781119530459
• Edition: 3
• Topic: Technik & Maschinenbau
• Subtopic: Agronomie

A student-friendly textbook that describes ancient soils, how they may be identified, and their use in paleoenvironmental reconstruction

Ancient soils contain vital mineralogical, geochemical, textural, and paleontological information about the continental environments in which they formed. Advances in isotope geochemistry and sequence-stratigraphic models allow evermore detailed reconstructions of environmental change from paleosols, and new insights into such diverse topics as atmospheric chemistry, global change, paleoecology, geobiology and mass extinction. This book educates readers about the field of paleopedology and how it remains a key area of investigation for geologists and environmental scientists seeking to learn about, and reconstruct, the condition and evolution of paleoenvironments.

Presented in three sections—Soils and Palesols; Factors in Soil Formation; and Fossil Record of Soils —Soils of the Past: An Introduction to Paleopedology describes the main types of ancient soil, procedures for identifying and studying them, their classification and, most significantly, a wide array of examples of how paleosols have been used for paleoenvironmental reconstruction. The book is an excellent reflection of the current state of knowledge and can be widely adopted over many disciplines.

• All chapters have been revised and updated to reflect advances in soil science in the last two decades
• New tables display a wealth of new data added since the 2nd edition published in 2001
• New figures have been added and line art has been redrawn to improve clarity and promote understanding
• References have been updated throughout

Soils of the Past, 3 rd Edition is written for advanced undergraduates studying paleopedology as part of a degree in geology, environmental science, or physical geography, and for interested professional earth scientists.

Part I
Soils and paleosols

Chapter 1
Paleopedology

Paleopedology is the study of ancient soils, and is derived from an ancient Greek word (πεδov, πεδoυ)for ground. It has nothing to do with pedestrians (Latin pes, pedis) or pediatricians (Greek παιs, παιδos). Soils of the past, either buried within sedimentary sequences or persisting under changed surface conditions, are the main subject matter of paleopedology. In this book, it is seen as an historical perspective on soil genesis and as a way of reconstructing the geological history of land surfaces on Earth. Soils, like organisms, sediments, and surface environments, have changed over the past 4567 million years of recorded Earth history.

Some understanding of soil burial and erosion can be inferred from classical Greek accounts by Plato in Athens, and by Herodotus in Egypt (Retallack 2013a), but the first demonstration of a fossil soil was by Luigi Marsigli (1726), whose military engineering report for Austro‐Hungarian Emperor Leopold I showed soil buried by alluvium near what is now Stari Slankamen, Serbia (Figure 1.1). Not much was made of this observation at the time, but Marsigli's buried Ustoll (calcareous Mollisol) is now known to be about 125 ka in age (Buggle et al. 2014). During the late nineteenth century, many such buried soils were widely recognized within Quaternary deposits of loess and till. These “weathered zones,” “forest zones,” and “soils,” as they were variously termed, were found in the Russian Plain by Feofilatkov (in the 1870s as recounted by Polynov 1927), in the midcontinental United States by McGee (1878), and near Timaru, New Zealand by Hardcastle (1889). By the turn of the century such observations had been used for the stratigraphic subdivision of glacial deposits (Chamberlain 1895).

Figure 1.1 Danube river terrace, showing modern soil (A = Terra fructifera pinguis nigra et cretaceo), over buried black soil (B = Terra nigra fructifera pinguis) with a subsurface horizon of carbonate nodules (C = Terra lutosa, cinericio et in fragmento cretacea priabilis), and floodplain (D = Ripa arenosa, qualis plerumq, Septentrionalis existet).

Source: From Marsigli 1726.

Much older paleosols were discovered by the Scottish physician James Hutton (1795), who regarded red rocks along angular unconformities of Devonian age in the River Jed and at Siccar Point, southeast of Edinburgh, as comparable with surface soils and sediments on the modern landscape (Figure 1.2). “From this it will appear, that the schistus mountains or vertical strata of indurated bodies had been formed, and had been wasted and worn in natural operations of the globe, before horizontal strata were begun to be deposited in these places...” (Hutton 1795, v. 1, p. 438). These ideas were reiterated in John Playfair's (1802) “Illustrations of the Huttonian Theory of the Earth” which, because of its conciseness and clarity of expression, was more influential than Hutton's original two volumes.

Figure 1.2 Angular unconformity between Early Silurian (430 Ma), Hawick Rocks and Late Devonian (360 Ma), Upper Old Red Sandstone along the river Jed in southeastern Scotland.

Source: From Hutton (1795).

The oldest record of buried soils within a consolidated sedimentary sequence were the “dirt beds” (Figure 1.3) and fossil stumps reported in the latest Jurassic limestones of the Dorset Coast by Webster (1826) and popularized in William Buckland's (1837) “Bridgewater Treatise.” Other fossil forests were discovered in the late nineteenth century, and their stumps and associated fossil plants described, but little was made of their substrates as fossil soils. Examples include the tourist attractions of Eocene Sequoia forests of Yellowstone National Park, USA, and Carboniferous stumps of tree‐lycopsids at Clayton (Yorkshire) and in Victoria Park (Glasgow), both in Britain (Seward 1898). While Seward appreciated the significance of fossil soils and their stumps as indicators of past worlds, study of the paleosols themselves had to await the development of soil science.

Figure 1.3 “Dirt beds” (paleosols) in a stratigraphic section through the latest Jurassic (Tithonian, 150 Ma), Purbeck formation on the Isle of Portland, Dorset, England.

Source: From Buckland (1837).

Despite these discoveries, the origin of paleopedology as a discrete field of inquiry can be traced back to the late nineteenth century development of soil science (Tandarich and Sprecher 1993). Since classical times, soils have been studied from the point of view of plant nutrition. It was not until 1862 that the Saxon scientist Fredrich A. Fallou first published the term “pedologie” for the study of soil science, as opposed to what he termed “agrologie,” or practical agricultural science. The foundations of modern soil science were laid by Vasily Dokuchaev with a detailed account of the dark, grassland soils of the Russian Plain (1883). This monograph demonstrated that soils could be described, mapped, and classified in a scientific fashion. Furthermore, their various features could be related to environmental constraints, of which climate and vegetation were considered especially important. By the early part of the twentieth cen...