What is a diachronous unit?
A diachronous unit is a time unit that is bounded by non-synchronous lower and upper boundaries. Such a period may be represented by the unequal lengths of time required for deposition of a lithostratigraphical or biostratigraphical unit.
What is progradation in geology?
Progradation is the diagnostic depositional trend for regressions, and is defined as the building forward or outward toward the sea of a shoreline or coastline (as of a beach, delta, or fan) by nearshore deposition of river-borne sediments or by continuous accumulation of beach material thrown up by waves or moved by …
What is a facies in geology?
1. n. [Geology] The overall characteristics of a rock unit that reflect its origin and differentiate the unit from others around it. Mineralogy and sedimentary source, fossil content, sedimentary structures and texture distinguish one facies from another.
What does time transgressive mean?
When they cut across facies boundaries the facies deposit is considered to be diachronous, or time transgressive.
What is the meaning of Chronostratigraphy?
Chronostratigraphy is the branch of stratigraphy that studies the ages of rock strata in relation to time. The ultimate aim of chronostratigraphy is to arrange the sequence of deposition and the time of deposition of all rocks within a geological region, and eventually, the entire geologic record of the Earth.
What is biostratigraphy for?
Biostratigraphy is the branch of stratigraphy that uses fossils to establish relative ages of rock and correlate successions of sedimentary rocks within and between depositional basins. A biozone is an interval of geologic strata characterised by certain fossil taxa.
What is Parasequence in geology?
A parasequence is a set of relatively conformable, genetically interrelated rock strata or stratal set that is bounded by marine flooding surfaces and their correlatable interfaces.
What is a facies map?
A map showing the distribution of different types of rock attributes or facies occurring within a designated geologic unit.
What does a lithofacies map display?
One of the most important tools for reconstructing ancient environments is a lithofacies map a map showing the distribution of rock types (lithofacies) in an area. If the rocks are the same age, this map records the relative positions of various environmental settings at that time in the past.
What is a transgression in geology?
1. n. [Geology] The migration of shoreline out of a basin and onto land during retrogradation. A transgression can result in sediments characteristic of shallow water being overlain by deeper water sediments. Antonyms: regression.
What is a transgressed?
1 : to violate a command or law : sin. 2 : to go beyond a boundary or limit. transitive verb. 1 : to go beyond limits set or prescribed by : violate transgress divine law.