Wedge Document

FIGURE 8.9. Flowchart A. Overall decision tree for evaluation on repro/developmental toxicity risk from Wedge Document, 1999, distributed through www.FDA.gov (June, 1999). 

On the other hand, in glassy polymers the zone of crack tip yielding is often found to be a thin wedge rather than a circle. It is now well documented that a good description of the shape and size of this yielded zone at the crack tip can be provided by the plastic zone size model proposed by Dugdale and by the cohesive force model of Barenblatt " . Similar solutions and further developments have been contributed by other authors... 

If Foerstia extends into northwestern Illinois, it should be found just below the base of the Saverton in the top of the western Grassy Creek. The sediment source for this great wedge of Hannibal/ Saverton and upper Grassy Creek above Foerstia would have been northwest, but the sediments below the presumed position of Foerstia in the Illinois Basin are not necessarily from that same source. Kepferle s (13) documentation of Foerstia on the eastern edge of the Illinois Basin has established that the great bulk of black shale in the Illinois Basin predates much of the black shale in eastern Kentucky and Ohio (27) and invalidates several recently published correlations. 

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