stratigraphy Flashcards
father of stratigraphy
nicolas steno
breaks due to variations in the normal processes in the environment
diastem
weathering and colonization of palnts
non-depositional diastem
migration of river channels
erosional diastem
changes in the base level of erosion or aggradation
non-depositional and erosional diastem
possesses charac that distinguish it from other parts of the formation
member
basic unit of stratigraphy
formation
basic unit of stratigraphy
formation
defined body of predominantly intrusive highly deformed and highly metarmophed rocks has boundaries placed at positions of lithic change
lithodemic
fundamental unit in lithodemic classification should posses distinctive lithic features and some degree of internal homegeneity
lilthodeme
two or more associated lithodemes of the same class
suite
it is a type of contact wherein it forms unbroken depostional sequences with layers deposited by uninterrupted deposition
conformable
refers to aspect, nature or manifestation of character or rock strata or specific constituents of rock strata
facies
facies adjacent to one another in a continuous vertical sequence also accumulated adjacent to one another laterally. 2 diff facies found superimposed on one another and not separated by unconformity must have deposited adjacent to each other at a given point in time
walther’s law
facies based on petrological characters such grain size and mineralogy
lithofacies
commonly preserved as buolbous or mamillia natural casts on the bottoms of sandstone beds
flute marks/flute casts
preserved on lower surfaces of sandstone beds as thin ridges
tool marks
sharply defined upper and lower surfaces enclosing or bounding beds
bedding plane
indicator of the depositional conditions under which the bed formed
bed shape
stratification thinner than 1cm produced by changes in the pattern of sedimentation
lamination
finely interbedded grain sizes such as sand and mud and can occur at a variety of scales
heterolithic bedding
0.5 to 3.0 cm in height with wavelengths 5 to 40 cm
less tahn 0.7 mm in diameter
ripples
typically have long straight parallel crests with bifurcations ripple index is high and rarely preserved
wind ripples
internal sedimentary structure of many sand grade and coarser sed rocks with a height of >6cm and thickness of 1cm or more
cross bedding