This is a graded discussion: 5 points possible due Mar Week 8-Discussion Board 1
ID: 288288 • Letter: T
Question
This is a graded discussion: 5 points possible due Mar Week 8-Discussion Board 14 There are big differences in North American depositional environments between the Mississippian and Pennsylvanian periods. While non-US geologists consolidate these periods into the "Carboniferous," US geologists felt a division was needed because of very different rock types and deposition within the Mississippian and Pennsylvanian. Can you hypothesize the different types of organisms that proliferated during these periods, and whether they contributed to the types of rocks that dominate each period? Please note that the instructor will read all of the students' posts as he grades them and will provide guidance and feedback as deemed necessary. Search entries or author UnreadExplanation / Answer
ANSWER-
The carboniferous Period defines a timeperiod from 359 to 259 Ma of geological age.The word "carboniferous" is derived from England for rich deposits of coal are found there.In the US however,the period is separated into Mississipian (L.carboniferous) and pennsylvanian(U.carboniferous) periods due to distinguishing depositional environments.The Mississipian was mainly limestone bearing whereas the pennsylvanian was coal bearing.
Organisms that contributed to the formation-
MISSISSIPIAN-
conodonts(Siphonodella Sulcata),fusulinid foram(pseudoschwagerina beedei of N.America),foraminifers,bryozoans,cryozoans etc.
PENNSYLVANIAN-
plant remains,swamps,seedless plants such as lycopsids,ferns , sphenopsids,subordinately snails,dragonflys,spiders, and appearance of amphibians .
There is a transition from a marine to terrestial environment seen from mississippi to pennsylvanian periods.
Most mississipian rocks are limestone mainly formed from crinoids,algae,CaCO3 by waves.
The pennsylvanian period on the other hand, due to alternating terrestial and marine conditions in additon to glacial trangression/regression witnesses huge plant material leading to the formation of coal forming strata.
Hence the subdivision of the carboniferous period is justified.
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