Compare and contrast histosols and aridosols, the soils of bogs and peat marshes versus those of deserts and arid regions respectively.

Prominent sea-level changes and climate fluctuations occurred during the past 103-105 years. Sea level changes strongly influence river behaviour and coastal development. Climate changes affect the discharge and sediment load characteristics of rivers and also the development of a protective vegetation cover that stabilises the landscape. Changes in sea level and/or climate induce changes in river type, channel pattern and sediment sequences. Climate changes during the (recent) Quaternary had a particularly strong impact. In (now) temperate regions, glacial climate was much drier and colder than today. Wet-tropical areas were drier as well. A belt of permafrost surrounded the large continental ice sheets and sea levels were some 120 m and perhaps even 135 m lower than today. There are strong indications that mass wasting processes such as frost weathering and `gelifluction' in high-relief areas were more prominent than today and that consequently the sediment loads of rivers were greater than at present. Once most of the Pleistocene ice cover had disappeared, some 6,000 years ago, the rate of sea level rise decreased and coasts adapted to the higher sea level. Today, (Pleistocene) glaciers that have long disappeared still influence some 15 percent of the land surface. It is impossible to understand the complexity of `landforms in lowlands' without referring to their present climate and their climatic history.

The light is great source of energy