Erg (landform) Erg (landform) An erg (also sand sea or dune sea, or sand sheet if it lacks dunes) is a broad, flat area of desert covered with wind-swept sand with little or no vegetative cover. The term takes its name from the Arabic word "ʿarq" (), meaning "dune field". Strictly speaking, an erg is defined as a desert area that contains more than of aeolian or wind-blown sand and where sand covers more than 20% of the surface. Smaller areas are known as "dune fields". The largest hot desert in the world, the Sahara, covers and contains several ergs, such as
ERG theory a lower category need. For example if self-actualization or self-esteem is not met then individuals will invest more effort in the relatedness category in the hopes of achieving the higher need. This theory was published originally in "Organizational Behavior and Human Performance". ERG theory ERG theory is a theory in psychology proposed by Clayton Alderfer. Alderfer further developed Maslow's hierarchy of needs by categorizing the hierarchy into his ERG theory (Existence, Relatedness and Growth). The existence group is concerned with providing the basic material existence requirements of humans. They include the items that Maslow considered to be physiological and safety