The geography of Scotland in the early modern era covers all aspects of the land in Scotland, including physical and human, between the sixteenth century and the beginnings of the Agricultural Revolution and industrialisation in the eighteenth century. The defining factor in the geography of Scotland is the distinction between the Highlands and Islands in the north and west and the Lowlands in the south and east. The Highlands were subdivided by the Great Glen and the Lowlands into the fertile Central Lowlands and the Southern Uplands. The Uplands and Highlands had a relatively short growing season, exacerbated by the Little Ice Age, which peaked towards the end of the seventeenth century.