1869.J GEOLOGY AND MINERALOGY. 349 



nate " Tertiary." The land was diversified more than before, — 

 more islands, more bays, more rivers, more seas ; hence a greater 

 variety of life in every shape, animal and vegetable, and not le:ist 

 in Entomostracu. 



From some beds of sand and clays we get Cytlieridea MueUcri, 

 such as now covers the estuarine nmds not far from moutbs of 

 rivers; in other beds we get Bairdia subdeltoidea, such as is 

 chiefly found in deep seas and warm climates : in another stratum 

 we get the carapaces of Ci/theres, such as we find in the shallow 

 water of our own coasts. Here we have evidences of the exist- 

 ence of different conditions of sea-bottoms, contemporaneous or 

 successive, as the case may be, in a series of deposits now con- 

 verted into clay or stone. 



Elsewhere we have layers of clay or stone filled and covered 

 with the shells of Ci/prides, as thickly strewn as in the mud of 

 any river now running. 



Tracing these river-deposits and these sea-deposits, the geologi-t 

 traces out the ancient outlines of land and sea in the long past 

 periods of the earth's history, of which we have no other record. 

 But this is a record sufficient ; and it teaches us, also, that not 

 only to great things but to small, not only to monster beasts — 

 Iguanodons, Elephants, Whales — but to microscopic Entomos- 

 traca, is our attention to be turned if wc wish to learn aright 

 what has passed on this earth's surface, if we wish to carefully 

 study God's creation, and to see all the evidences of perfect 

 design and perfect adaptation that the history of successive forms 

 of life, with their successive modifications of structure and habits, 

 can supply. 



Boulder Clay. — Is Boulder Clay a marine or land deposit. 

 formed by glaciers or by icebergs, or is it of both or of several 

 origins? These questions, in so far as they relate to the Till or 

 Boulder Clay of Scotland, are ably discussed as follows by Mr. 

 Crosskey, in the transactions of the Glasgow Geological Society : 



Under the general term, boulder clay, many deposits produced 

 at various periods during the great glacial epoch, and by different 

 causes have been loosely included. It is necessary to distinguish 

 between these various ' Boulder Clays," before observers in 

 separate localities will be able to understand each other's language, 



