Understanding Earth history involves determining the sequence of geologic events

Question

Understanding Earth history involves determining the sequence of geologic events which occurred over immense spans of time. The geological time scale that we use today was first developed in the 1800's and is constantly being revised as our understanding improves. Geologists deal with time in two different ways: Relative Time - the occurrence of events is determined relative to one another (from oldest to most recent). This can be a local series of events or be applied to global events. The eras and periods of the geological time column were established using relative time (mostly based upon the fossil content) Absolute Time - The discovery of radiometric dating allowed geologists to assign a numerical age to the formation of certain rocks. Fixing how old they actually were in billions (Ga), millions (Ma) or thousands (Ka) of years before the present. Hence the term "absolute" time These two ways of looking at time are not unique to geologists. You use them everyday. If you agree to meet a friend "after class" - that is a relative time. The time of day when you actually meet is dependent upon when your class is scheduled and when it is finished. If instead you arrange to meet at 1:00pm that is absolute time.

Explanation / Answer

Exercise 2 the sequence: common layer is K in first two columns and S is common and older than K in 2nd and third columns. S is older than M and D, therefore S is the oldest of all. Except S, no other layer is older than D, therefore D is the next younger layer. Next younger layers to D in the image can be J, M,T J is younger than T (column 5) and T is younger than M(column 5), therefore M is younger than D and it cannot be P as it is younger than M. layers younger to M are T,P,J T is younger than P and J is younger than T , therefore P is the next younger layer. T is older than J (column 6), J is older than K (column 2) and K is older than C column 1). therefore the order is T,J,K,C the complete order from youngest to oldest is C,K,J,T,P,M,D,S

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