In our own country the forest growth has been much interfered with by man, but the lower fenland peat gives a good example of the material formed by forest growth. It is not necessary to touch on the various accumulations which are now being formed in different parts of our island, except to remark that the deposits of the Forest period give indications of earth-movements on a small scale, which is well seen in the fenland, where the forest peat is covered in places by a "buttery clay" with _Scrobicularia piperata_ indicating submergence, and above this is a marsh peat. The flora and fauna of the Forest period are practically those of the present day, though the larger forms of mammalia have disappeared one by one. The Irish elk and _Bos primogenius_ probably became extinct early in the period, while as far as Britain is concerned the wolf, bear, and beaver have disappeared within historic times. The relics of man deserve passing notice. The Neolithic period is characterised by the absence of metal instruments, though those made of stone were much more highly finished than those of Palæolithic times, and were often ground and polished. The first metal which was largely worked was bronze, which gradually replaced stone, though stone was extensively used in the Bronze age, as indicated by the imitation of bronze implements in stone. The Bronze age in turn was replaced by the Prehistoric iron age; at first, when iron was scarce, bronze implements were merely tipped with iron, but ultimately the one metal was practically replaced by the other. The date of the Palæolithic period is unknown; no approximate date can be satisfactorily assigned to it, but various calculations, founded on different data, have been made as to the age of the Neolithic period, and several of them agree in placing it at about 7000 years from the present time. It will be seen that no sudden and violent change marks the incoming of the human race, which to the geologist is but one of a large number of events which have followed each other in unbroken sequence, and accordingly the thread of the story where abandoned by the geologist is taken up by the antiquary, and passed on by him to the historian[118]. [Footnote 118: The student may obtain information concerning the Neolithic age in Britain in Boyd Dawkins's _Early Man in Britain_; Sir J. Evans' _Early Stone Implements of Great Britain_, and Sir J. Lubbock's _Prehistoric Times_. In the latter work he will find a good account of the Neolithic remains of Denmark and of the Swiss Lake dwellings. For information concerning the Bronze age he should consult Evans' _Ancient Bronze Implements of Great Britain_. The varied Danish antiquities of Neolithic and Bronze ages are figured in H. P. Madsen's _Antiquités Préhistoriques du Danemark_. The Prehistoric fauna of the fenlands is described in Sir R. Owen's _History of British Fossil Mammals and Birds_.] CHAPTER XXX. REMARKS ON VARIOUS QUESTIONS.