WHAT IS THE DRYAS ?

A series of cold climatic phases in northwestern Europe, during a time when the North Atlantic was in almost full glacial condition. Dryas I was c. 16,000–14,000 bp, Dryas II (Older Dryas) was c. 12,300– 11,800 bp, and Dryas III (Younger Dryas) was c. 11,000–10,000 bp. It is named after a tundra plant. The increasing temperature after the late Dryas period during the Pre-Boreal and the Boreal (c. 8000– 5500 bc, according to radiocarbon dating) caused a remarkable change in late glacial flora and fauna.

WHAT IS THE ATLANTIC PERIOD ?

ATLANTIC PERIOD: in Europe, a climatic optimum following the last Ice Age. This period was represented as a maximum of temperature, and evidence from beetles suggests it being warmer than average for the interglacial. It seems to have begun about 6000 bc, when the average temperature rose. Melting ice sheets ultimately submerged nearly half of western Europe, creating the bays and inlets along the Atlantic coast that provided a new, rich ecosystem for human subsistence. The Atlantic period was followed by the Sub-Boreal period. The Atlantic period, which succeeded the Boreal, was probably wetter and certainly somewhat warmer, and mixed forests of oak, elm, common lime (linden), and elder spread northward. Only in the late Atlantic period did beech and hornbeam spread into western and central Europe from the southeast.

WHAT IS THE ANGLIAN ?

ANGLIAN: Quaternary glacial deposits found in East Anglia, England. Other possibly related and isolated patches exist elsewhere in Britain, but they are older than the extreme range of radiocarbon dating and paleomagnetism shows them to be younger than 700,000 bp. This period sometimes equates with the Elster glacial maximum and dates to c. 400,000–300,000 years ago. During the Anglian-Elsterian glaciation in Europe a large ice-dammed lake formed in the North Sea, and large

overflows from it initiated the cutting of the Dover Straits. In East Anglia, the deposits are stratified below Hoxnian and above Cromerian interglacial deposits, and Acheulian and Clactonian artifacts are found in the sediments. Most of the evidence of human activity in Britain and Europe is later than this time. Anglian is more often used to describe the group of deposits or the one glaciation (antepenultimate) of that time.

WHAT IS THE ANDEAN CHRONOLOGY ?

ANDEAN CHRONOLOGY: chronological systems of the Central Andes area with two main stages, Preceramic and Ceramic. The Ceramic is broken down into: Initial Period, 1900–1200 bc, Early Horizon 1200–300 bc, Early Intermediate Period 300 bc to ad 700, Middle Horizon 700–1100, Late Intermediate Period 1100–1438/1478, and Late Horizon 1438–1532. These Horizon periods are times of widespread unity in cultural traits. Intermediate periods are times of cultural diversification.

WHAT IS THE ALTITHERMAL ?

ALTITHERMAL: A warm, dry postglacial period in the western United States c. 5600–2500 bc. Coined by Ernst Antev in 1948, the term describes a time during which temperatures were warmer than at present. Other terms, like “long drought,” are also used.

WHAT IS THE ALLEROD OSCILLATION ?

ALLEROD OSCILLATION: An interstadial (transient) period of glacial retreat at the close of the Würm glacial stage in Europe, dated to c. 12,000– 11,000 years ago. This temporary increase in warmth allowed forests to establish themselves for a time in the ice-free zones. Radiocarbon dates show similar conditions prevailed in North America at about the same time. It was followed by another cold, glacial advance.