This book describes and discusses the physical, chemical, and biological characteristics of sedimentary rocks and the interpretations that we draw from these characteristics about the origin of sedimentary rocks
. 
Geologists disagree somewhat
about how the various kinds of sedimentary rocks should be classified; however,
such rocks can conveniently be placed into three fundamental groups on the basis
of composition and origin: siliciclastic, chemical/biochemical, and carbonaceous.
Siliciclastic sedimentary rocks are composed dominantly of silicate minerals,
such as quartz and feldspar, and rock fragments (clasts).
This book describes and discusses the physical, chemical, and biological characteristics of sedimentary rocks and the interpretations that we draw from these characteristics about the origin of sedimentary rocks These materials originate
mainly by the chemical and physical breakdown (weathering) of igneous, metamorphic, or (older) sedimentary rock. Conglomerates, sandstones, and shales belong to this group. Silicate detritus, including silicate minerals, rock fragments, and glass shards, can also be generated by explosive volcanism. Siliciclastic sedimentary rocks that formed mainly from the products of explosive volcanism are called volcaniclastic rocks.
Chemical/biochemical sedimentary rocks are composed of minerals precipitated mainly from ocean or lake water by 'inorganic (chemical) and/or organic (biogenic) processes. They include limestone, chert, evaporites such as gypsum, phosphorites, and iron-rich sedimentary rocks. Evaporites are probably precipitated entirely by inorganic processes resulting from evaporation of lake or seawater. Biogenic processes, as well as inorganic processes, play an important tole in the formation of many limestones and likely play some role in the origin of .chert, phosphorites, and iron-rich sedimentary rocks. Carbonaceous sedimentary rocks contain a substantial amow1t (>-15 %) of highly altered remains of the soft tissue of plants and animals, referred to as organic matter.
The principal carbonaceous rocks are coal and oil shale. Carbonaceous sedimentary rocks make wp only a small fraction of the total sedimentary record; however, these rocks (especia11y coals) have great economic importance as fossil fuels.
This book describes and discusses the physical, chemical, and biological characteristics of sedimentary rocks and the interpretations that we draw from these characteristics about the origin of sedimentary rocks These materials originate
mainly by the chemical and physical breakdown (weathering) of igneous, metamorphic, or (older) sedimentary rock. Conglomerates, sandstones, and shales belong to this group. Silicate detritus, including silicate minerals, rock fragments, and glass shards, can also be generated by explosive volcanism. Siliciclastic sedimentary rocks that formed mainly from the products of explosive volcanism are called volcaniclastic rocks.
Chemical/biochemical sedimentary rocks are composed of minerals precipitated mainly from ocean or lake water by 'inorganic (chemical) and/or organic (biogenic) processes. They include limestone, chert, evaporites such as gypsum, phosphorites, and iron-rich sedimentary rocks. Evaporites are probably precipitated entirely by inorganic processes resulting from evaporation of lake or seawater. Biogenic processes, as well as inorganic processes, play an important tole in the formation of many limestones and likely play some role in the origin of .chert, phosphorites, and iron-rich sedimentary rocks. Carbonaceous sedimentary rocks contain a substantial amow1t (>-15 %) of highly altered remains of the soft tissue of plants and animals, referred to as organic matter.
The principal carbonaceous rocks are coal and oil shale. Carbonaceous sedimentary rocks make wp only a small fraction of the total sedimentary record; however, these rocks (especia11y coals) have great economic importance as fossil fuels.
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