How the hostile kings of Israel and Syria came to fight a common enemy, and how to correlate the Assyrian and Biblical records, are questions which have perplexed all recent writers.
We cannot yet say, however, that the deposits are exactly contemporaneous, and the great climatic variations that have taken place in the northern hemisphere during the existence of our living flora should make us hesitate to correlate too minutely from the evidence of plants alone.
It is unfortunately still very difficult to correlate even approximately the strata on the two sides of the Atlantic, and there is great doubt as to what strata belong to each division of the Tertiary period even in different parts of North America.
It has not yet been found possible so closely to correlate the strata of Europe with those of America, where distance has allowed geographical differences in both fauna and flora to come into play; therefore, beyond the references to Lower or Upper Cretaceous, no classification of the American Cretaceous strata has here been given.
Van Tieghem and his pupils, and others, who have sought to correlate the large mass of facts and to find some general underlying principles (see Plants: Anatomy of).
Many attempts have been made to correlate the results of the analyses of a soil with its known cropping power, but there is yet much to be learnt in regard to these matters.
If, however, we discover plantbearing strata interstratified with deposits containing marine fossils, we can fix the period to which the plants belong, and may be able to correlate them in distinct areas, even though the floras be unlike.
More and more the science seeks to discover periodicities and to correlate these with others.
To add to the educational value of the display, information as to the methods of feeding would be desirable, as it would then be possible to correlate the quality of the meat with the mode of its manufacture.
Eisner points out that homicide rates correlate well to levels of robbery, assault, and sexual violence across multiple countries and there is reason to believe it was so in the past as well.