Droughts, extensive in area and in duration, are by no means uncommon.
The inland region, called the sertao, is high, stony, and dry, and frequently devastated by prolonged droughts (seccas).
27a or fall in droughts more than 4 or 5 ft.
To the Volga, is less favoured by nature; the winters are longer and more inclement, and droughts are not uncommon.
Similarly secular elevations of temperature, either accompanied by moisture or desiccation, by increasing droughts or by disturbance of the balance of nature, have been followed by great waves of extinction of the Mammalia.