composed of vast beds of intermingled sands, gravels, mud, and organic débris, brought together by the action of rivers, sea-currents, etc., and rearranged into stratified layers—thus proving that they are mostly of aqueous origin. The reappearance of some of these sedimentary deposits as dry land, often rising to the height of mountains, shows that, pari passu with the action of the disintegrating and denuding agencies, oscillations in the relative level of sea and land were taking place in several localities. The causes of this variableness in land-areas so affected the portion of Europe now known as Great Britain that, from time to time, it assumed very different aspects, now forming part of a European continent, and again reduced to a mere speck in the Atlantic Ocean. These disturbing elements extended over a geological range of some 50,000,000 years, and during all that time the British area was a variable quantity. And even at the present time this instability has not altogether ceased, as we see extensive alterations going on around our shores, here increasing and there reducing our sea-board lands.
The statement that Britain was part of a European continent, when Palæolithic man first appeared as a naked savage among its woods and river-valleys, is not a haphazard assertion, but one founded on indisputable evidences. The numerous animals, many of them now extinct, which then found their way into Britain, such as the mammoth, rhinoceros,
