(fy&ftt&i 23 



STRATIGRAPHIC 

 CORRELATION 



L. W. LeRoy 



Correlation of stratigraphic units permits establishment of formational 

 sequences, evaluation of contemporaneous and noncontemporaneous deposits, 

 recognition of unconformities, reconstruction of paleotectonic fabrics, and de- 

 lineation of sedimentational patterns. 



During the past 20 years many new ideas, methods, and approaches in 

 stratigraphic geology have increased the accuracy with which stratal and 

 paleontological units can be correlated. The introduction of statistics into 

 stratigraphic geology has been responsible, partly, for this new thinking; 

 however, much more remains to be done in the way of integrating and interpret- 

 ing accumulated stratigraphic data. 



In some areas, correlation of stratigraphic units is difficult, if not impossible ; 

 in others, no serious problem exists. To treat adequately this range of situations, 

 the geologist must be familiar with the fundamentals of correlation and able to 

 analyze stratigraphic conditions so as to determine what procedure or procedures 

 (and their limitation) are applicable in solving them. 



STRATIGRAPHIC UNITS Before the correlation of deposits is attempted, 



it is essential that stratigraphic units be de- 

 fined accurately. Schenck and Muller (1941) recommended that continued use 

 be made of three types of stratigraphic units as a basis for correlation: (1) 

 lithogenetic (rock), (2) time-stratigraphic (time-rock), and (3) time. 



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