210 Review of *' Outlines of the 



rine Zoophytes," as well as volcanic products, are not 

 reckoned as alluvial. In the work before us, particular 

 descriptions of this, as well as the next formation, are re- 

 served for the second part ; because a knowledge of the 

 regular strata, from which they are derived, seemed previ- 

 x)usly requisite. We perceive, however, that no place is 

 given, on the map accompanying this work, to alluvial*; we 

 suppose because its extent, in great Britain, is so extremely 

 limited. 



Were the geological maps of North- America, that have 

 been published, to be made a standard, we must conclude, 

 that the alluvial is one of the most extensive of our forma- 

 tions. There can be little doubt, however, that under this 

 term our geologists have included a// <^05e strata, that are 

 not consolidated, if so, not one thousandth part of those 

 tracts, marked as alluvial in this country, really belongs to 

 that formation. It cannot be doubted however that along 

 our rivers, especially the larger ones, and at their mouths, 

 examples of alluvium are not very unfrequent. The delta 

 of the Mississippi furnishes a noble instance. 



Diluvial. Immediately below the alluvium " we find a 

 mantle as it were of sand and gravel indifferently covering 

 all the solid strata, and evidently derived from some convul- 

 sion which has lacerated and partially broken up those stra- 

 ta, inasmuch as its materials are demonstrably fragments of 

 the subjacent rocks, rounded by attrition.'' " The frag- 

 mented rocks constituting these gravel depositesare heap- 

 ed confusedly together, but still in such a manner that the 

 fragments of any particular rock will be found most abund- 

 antly in the gravel of those districts, where the parent 

 rock itself appears, in situ, among the strata. In these de- 

 posites, and almost in these alone, the remains of numerous 

 land animals are found, many of them belonging to extinct 

 species and many others no longer indigenous to the coun- 

 tries where their skeletons are thus discovered." (p. 4.). 

 We can only add the concluding remark : " It has there- 

 fore, from the most probable views concerning the nature 

 of this great catastrophe, been proposed to designate these 

 formations, which naturally constitute the second term of 

 our geological series, Diluvial.^^ 



* We believe this is a mistake. The Fens of Lincolnshire, and Ely, and 

 some part? of the coast of Lancashire are so characterised. — [E<^-J 



