Publication 51 Origin, Classification and Use of ONTARIO SOILS Origin, Classification and Use of Ontario Soils by L. R. Webber and D. W. Hoffman Department of Soil Science Ontario Agricultural College University of Guelph CONTENTS Foreword 1 BEDROCK GEOLOGY 3 Rocks and Minerals 4 Classification of Rocks 4 Age of Rocks 6 Niagara Escarpment and the Falls 8 NATURAL VEGETATION 9 CLIMATE 11 Temperature 11 Precipitation 12 Kôppen Classification of Climates 12 GLACIERS AND GLACIAL ACTION 21 Kinds of Deposits 22 Recession of the Glacier 24 SOIL FORMATION 32 Additions 32 Removals 32 Transformations 33 Translocations 33 SOIL CLASSIFICATION 34 Interpretive Classification 34 Taxonomic Classification 35 Categorical Classification 36 GENERALIZED DESCRIPTION OF THE ORDERS AND GREAT GROUPS 39 Podzolic Order 39 Brunisolic Order 41 Gleysolic Order 41 Regosolic Order 44 Organic Soils 44 SOILS OF SOUTHERN ONTARIO 45 Clay Loams and Clays 46 Loams 49 Sands and Sandy Loams 51 SOILS OF NORTHERN ONTARIO 55 FOREWORD The history of the soil beneath our feet is fascinating and exciting. Yet much of the history remains unknown. The purpose of this publication is to outline the story of the soils of Ontario insofar as it is known, to give the broad description and classification of the soils and finally to show the relationship of the soil properties to the present and potential use of the soils for agriculture. The information contained herein is based on the careful observations of many people—geologists, climatologists, soil scientists and others who have studied the face of Ontario over many years. Among these is L. J. Chapman of the Ontario Research Foundation who has spent almost a lifetime studying the physiography of Ontario and who has been most helpful in preparing the section on "Glaciers and Glacial Action". D. M. Brown, formerly of the Ontario Research Foundation, was of great assistance in the preparation of the section on "Climate". During the past thirty years, the Canada Department of Agriculture and the Ontario Department of Agriculture have jointly carried out field studies and prepared reports on the soils in most areas of the Province. This information forms the basis for much of the description of soils and land use contained in this publication. Finally the advice of several members of the Department of Soil Science, University of Guelph, and of the Research Branch, Canada Department of Agriculture, was invaluable in the preparation of the manuscript. 1 Figure 1. The photograph on the left is limestone bedrock as it occurs along a roadside. The photograph on the right shows the shallow profile developed from glacial materials deposited over the bedrock. BEDROCK GEOLOGY Soil, Parent Material, and Bedrock parent material. In the glaciated regions of the world, Soil has been defined as the outer layer of the which include all of Canada, soils have developed from earth's crust, ranging in thickness from a mere film to their underlying parent material; in un-glaciated regions several feet and is underlain by material that has soils may have developed from the underlying parent different physical, chemical and biological properties. bedrock. Soil is generally recognized as having developed from In Ontario the mineralogical composition of many the underlying unconsolidated material, which is called parent materials is dependent on the composition of the parent material. The parent material is underlain by underlying bedrock; the mineralogical composition of bedrock. The depth to bedrock varies greatly from place other parent materials is not directly related to the to place. underlying bedrock because the materials have been In Figure 1, soil, parent material and limestone transported from other places during and immediately bedrock are all exposed. Although the parent material after glaciation. The section that follows outlines the contains many fragments of the limestone it also in- distribution of the various kinds of bedrock in Ontario cludes fragments which are of sedimentary, meta- and describes some of their properties that may have morphic, and igneous derivation. One must assume that contributed to significant properties of the soil parent this parent material was brought in and deposited over material. the bedrock and that a soil has developed from the 3 Figure 2. A rock cycle. By the weathering and erosion of all kinds of rocks, sediments are made available that may be fused to form igneous rocks or by pressure and cementing agents are transformed into sedimentary rocks. Metamorphic rocks are formed from either sedimentary or igneous rocks. ROCKS AND MINERALS CLASSIFICATION OF ROCKS A mineral is a naturally occurring homogeneous inorganic substance whose composition may be Rocks are usually divided into three main classes expressed by a chemical formula, for example, calcite depending on their assumed mode of formation CaCO3, quartz SiO2. (Figure 2). A rock may be defined as naturally occurring solid Igneous Rocks material consisting of two or more minerals. Granite is It is thought that igneous rocks originated at great a rock that contains the minerals feldspar, quartz, and depths in the earth's crust where the temperature was mica. high enough to cause melting. Molten magma that reached the surface, cooled quickly and resulted in fine or small crystals. The magma that cooled slowly at greater depths within the earth had a longer time for the crystals to grow and formed coarse grained rocks, such as granite (Figure 3) . 4 Figure 3. Mineral composition and texture are two properties that may be used to classify igneous rocks. In general all rocks < Decreasing silica content in a horizontal division in the above table are alike in < increasing iron and magnesium minerals texture but because of minor differences in mineral < changing from potassium to sodium and lime composition, a great many rocks occur between granite and feldspars gabbro. In any vertical column the chemical composition < increasing content of dark minerals is similar but many separations are possible in grain size between granite and rhyolite. Igneous rocks are classified chemically as acidic, igneous rocks. neutral or basic, depending on their content of silica. Sandstone - sand that has been consolidated by Highly siliceous rocks are acidic. pressure and cementation Granite — an acidic gray, white, or pink rock with - common cementing agents include distinguishable grains of quartz and silica, calcium carbonate, and the feldspar. The chemical formula of hydroxides of iron and aluminum. microcline, a common feldspar, is Shale - a consolidation of fine sediments, KAlSi3O8. mostly clay. Rhyolite — a dense acidic rock of chemical compo- - a soft, fine-grained, and laminated sition similar to granite but with indis- rock. tinguishable grains. Gabbro — a basic dark-colored granular rock con- Metamorphic Rocks taining feldspar and pyroxene minerals. The term metamorphic implies "changed" or "altered". Basalt— similar to gabbro but fine-grained. The common causes of change are pressure and heat. Most igneous and sedimentary rocks have metamorphic Sedimentary Rocks equivalents. Sedimentary rocks were formed from deposits of Gneiss from granite - coarsely banded or streaked gravel, sand, silt, or clay that had been transported and rock. laid down in shallow seas or lakes. The sediments were Schist from shales or shaly rocks - fine-grained; consolidated into rock by the weight of the overlying foliated structure. accumulations and by the cementing action of various Quartzite from sandstone - dense rock; quartz sand materials such as silica and calcium carbonate. cemented with silica. Limestone — two possible sources; Slate from shale - splits into thin, dense sheets. (1) the remains of the shells of sea animals, Marble from limestone—dense, nonporous calcium or carbonate. (2) a chemical precipitation in sea water. The rate of weathering of metamorphic rocks depends Dolomite — a mixture of calcium and magnesium on the degree of metamorphism and the minerals in the carbonates, usually denser than limestone. rocks, for example, feldspars weather more quickly than The calcium and magnesium in limestone and dol- quartz. omite were derived originally from the minerals in 5 geologic time scale is subdivided into eras, periods, and AGE OF ROCKS in some cases epochs (Table 1). The basis of a subdivision is the evidence of some major event in geological history. For example, the formation of the Historical geology deals with the age of rocks and Appalachian mountains along the eastern side of North with the evidence that exists of plant and animal life America caused the expulsion of a great sea that had associated with the formation of the various rocks. The existed for millions of years in that region. TABLE 1. Major Eras, Periods And Epochs Of A Geological Time Scale. The periods and epochs found in Ontario are shown in bold type. ERA PERIOD EPOCH ASSOCIATED EVENTS YEARS AGO* CENOZOIC Quaternary Recent < modern man 11,000 Pleistocene < early man 0.5 to 2 million < glaciations Tertiary several < beginning of mammals 1 to 60 million < exposed rocks of this period found in Manitoba and other parts of Western Canada Cretaceous < lignite south of James Bay formed in this 60 to 130 million period MESOZOIC Jurassic < appearance of first birds 130 to 180 million < age of dinosaurs Triassic < conifers; dinosaurs 180 to 230 million < coastal range of Rocky Mountains appeared Permian < cold arid climate 250 million < beginning of Appalachian Mountains Carboniferous < great coal deposits 300 to 350 million < first reptiles PALEOZOIC Devonian < fishes abundant 350 to 400 million < oil-bearing rocks in South-western Ontario Silurian < salt and gypsum deposits in Ontario 400 to 425 million < first land plants Ordovician < first fishes 425 to 500 million < exposed rocks east of the escarpment in Ontario Cambrian < sandstones in Eastern Ontario and near 500 million to 600 million Lake Superior < peaks in eastern range of Rocky Mountains PRE- 2 eras < fossils are rare 600+ million CAMBRIAN < era of extensive metamorphism < these rocks underlie all later formations in Ontario * This column indicates in a general way the estimated "years ago" that a period or epoch began.