My Object Will Be, First,

Secondly, The Nature Of The Revolutions Which Have Altered The Surface Of The Earth Must Have Had A More Decisive Effect On The Terrestrial Quadrupeds Than On The Marine Animals.

The Lowest And Most Level Land Areas Show Us, Especially When We Dig There To Very Great Depths, Nothing But Horizontal Layers Of Material More Or Less Varied, Which Almost All Contain Innumerable Products Of The Sea.

It Is Evident That One Cannot Say Anything Demonstrable About The Problem Before Having Resolved These Preliminary Questions, And Yet We Hardly Possess The Necessary Information To Solve Some Of Them

It Has Been Long Considered Possible To Explain The More Ancient Revolutions On... The Earth Surface By Means Of These Still Existing Causes; In The Same Manner As It Is Found Easy To Explain Past Events In Political History, By An Acquaintance With The Passions And Intrigues Of The Present Day. But We Shall Presently See That Unfortunately This Is Not The Case In Physical History:-the Thread Of Operation Is Here Broken, The March Of Nature Is Changed, And None Of The Agents That She Now Employs Were Sufficient For The Production Of Her Ancient Works.

It Is My Object, In The Following Work, To Travel Over Ground Which Has As Yet Been Little Explored And To Make My Reader Acquainted With A Species Of Remains, Which, Though Absolutely Necessary For Understanding The History Of The Globe, Have Been Hitherto Almost Uniformly Neglected.