sedimentary structures Flashcards
list of sed. structures
cross bedding graded bedding flute casts imbricate structure salt pseudomorphs desication cracks ripple marks
sed structures found on bedding planes
flute cast
ripple marks
desication cracks
sed structures found within beds
salt pseuodomorphs
graded bedding
cross bedding
imbricate structure
way up/paelocurrent indicator? CROSS BEDDING
both
way up/paelocurrent indicator? GRADED BEDDING
way up
way up/paelocurrent indicator? IMBRICATE STRUCTURE
paelo current
way up/paelocurrent indicator? SALT PUESDOMORPHS
none
way up/paelocurrent indicator? RIPPLE MARKS
yes (paelocurrent if assymetical)
way up/paelocurrent indicator? DESICATION CRACKS
way up
way up/paelocurrent indicator? FLUTE CASTS
both
angle of cross bedding
less than 37 degrees
turbitity flow indicators
flute casts
sometimes graded bedding
what is the difference between symettrical and assymetrical ripple marks
symetrical: water flows both ways i.e. beach slatating grains move both ways with swash and backswash
assymetrical: water flows one way, indicating direction of current, as saltation carries graisn
where do desication cracks form
in clay- rich sediments
what is a flute cast
found at bottom of a bed
result of erosion caused by turbulent flow (usually over soft mud)
form parallel to current
deeper the more upstream