394 



that the association of the leading Ammonites at the junction 

 of the Zones in question, the 8pinatus and the Upper Margari- 

 tatus, is not infrequent, whilst the fauna of each indicates a 

 sufficient difference to afford a criterion. This digression will 

 assist us to usher in the correlation of U. Schlonbach, which 

 is identical with our own, and based upon similar grounds. 



Die Schichtenfolge des unt. Mittl, Lias in NorddeutscM. p. 168, 1863. 

 MIDDLE LIAS. N. GERMAITY. 



The other work of U. Schlonbach "Ueber den Eisenstein des 

 mittleren Lias im N. W. Deutschlands," 1863, confirms 

 distinctly the same view, by numerous details, which assist us 

 materially in dieting the truth and obtaining trustworthy data. 

 Amongst many sections of the crowning beds of the Middle 

 Lias that wiU bear out this correlation, we select from those of 

 Harzburg, Liebenburg, Haverlah, and Calefeld, sections which 

 all display the Spinatus Zone, as in the profile below. 



SECTION OP THE SPINATUS ZONE. 

 HARZBURG. 



According to U. Schlonbach, there are exposures of Middle 

 Lias throwing light upon the succession of the strata of the 

 Upper Zones, at Liebenburg not far from Goslar. The section and 

 description he gives at p. 488 et passim, yield us much insight. 



