Clast
A fragment or grain produced by the physical or chemical weathering of a pre-existing rock. (page 211)
Sedimentary rock
Rock that forms either by the cementing together of fragments broken off preexisting rock or by the precipitation of mineral crystals out of water solutions at or near the Earth's surface. (page 211)
Sandstone
Coarse-grained sedimentary rock consisting almost entirely of quartz. (page 212)
Erosion
The grinding away and removal of the Earth's surface materials by moving water, air, or ice. (page 212)
Deposition
The process by which sediment settles out of a transporting medium. (page 213)
Lithification
The transformation of loose sediment into solid rock through compaction and cementation. (page 213)
Compaction
The phase of lithification in which the pressure of the overburden on the buried rock squeezes out water and air that was trapped between clasts, and the clasts press tightly together. (page 214)
Cementation
The phase of lithification in which cement, consisting of minerals that precipitate from groundwater, partially or completely fills the spaces between clasts and attaches each grain to its neighbor. (page 214)
Cement
Mineral material that precipitates from water and fills the spaces between grains, holding the grains together. (page 214)
Breccia
Coarse sedimentary rock consisting of angular fragments; or rock broken into angular fragments by faulting. (page 216)
Conglomerate
Very coarse-grained sedimentary rock consisting of rounded clasts. (page 217)
Siltstone
Fine-grained sedimentary rock generally composed of very small quartz grains. (page 217)
Shale
Very fine-grained sedimentary rock that breaks into thin sheets. (page 217)
Mudstone
Very fine-grained sedimentary rock that will not easily split into sheets. (page 217)
Biochemical limestone
Limestone incorporating shells produced by organisms. (page 218)
Coal
A black, organic rock consisting of greater than 50% carbon; it forms from the buried and altered remains of plant material. (page 219)
Oil shale
An organic shale containing abundant kerogen. (page 220)
Evaporate
To change state from liquid to vapor. (page 220)
Travertine
A rock composed of crystalline calcium carbonate (CaCO3) formed by chemical precipitation from groundwater that has seeped out at the ground surface. (page 221)
Sedimentary structure
A geometry or arrangement of material in sediment or sedimentary rock that formed during or shortly after deposition, not in response to later tectonic stress; examples include cross beds and mudcracks. (page 224)
Bed
An individual layer of sediment or sedimentary rock in a deposit. (page 224)
Strata
A succession of several layers or beds together. (page 224)
Bedding
Layering or stratification in sedimentary rocks. (page 224)
Stratigraphic formation
A recognizable layer of a specific sedimentary rock type or set of rock types, deposited during a certain time interval, that can be traced over a broad region. (page 224)
Ripple mark
Relatively small elongated ridges that form on a sedimentary bed surface at right angles to the direction of current flow. (page 224)
Dune
A pile of sand generally formed by deposition from the wind. (page 226)
Cross bed
Internal laminations in a bed, inclined at an angle to the main bedding; cross beds are a relict of the slip face of dunes or ripples. (page 226)
Mud crack
A small fissure in a fine-grained sediment that forms when the sediment dries; mud cracks are arranged to outline the shape of polygons. (page 227)
Paleosol
Ancient soil preserved in the stratigraphic record. (page 228)
Depositional environment
A setting in which sediments accumulate; its character (fluvial, deltaic, reef, glacial, etc.) reflects local conditions. (page 229)
Redbed
A sedimentary rock layer displaying a reddish color due to the occurrence of iron oxide minerals; such rocks typically form in terrestrial deposits. (page 230)
Alluvial fan
A gently sloping apron of sediment dropped by an ephemeral stream at the base of a mountain in arid or semiarid regions. (page 234)
Delta
A wedge of sediment formed at a river mouth when the running water of the stream enters standing water, the current slows, the stream loses competence, and sediment settles out. (page 234)
Subsidence
The vertical sinking of the Earth's surface in a region, relative to a reference plane. (page 237)
Sedimentary basin
A depression, created as a consequence of subsidence, that fills with sediment. (page 237)
Transgression
The inland migration of shoreline resulting from a rise in sea level. (page 238)
Regression
The seaward migration of a shoreline caused by a lowering of sea level. (page 238)
Diagenesis
All of the physical, chemical, and biological processes that transform sediment into sedimentary rock and that alter the rock after the rock has formed. (page 239)