Half a century before this, Scandinavian archaeologists had created a revolution in antiquarian thought by postulating, on archaeological grounds, successive technological stages in man’s past. C.J. Thomsen classified the material in the Copenhagen Museum, opened to the public in 1819, on the basis of three successive ages of Stone, Bronze, and Iron. His pupil and successor, J.J.A. Worsaae, showed the correctness of this museum arrangement by observed stratigraphy in the Danish peat bogs and barrows (funerary mounds). Low lake levels in Switzerland in the mid-1850s permitted the excavation of the prehistoric Swiss lake dwellings, and here again the theory of a succession of technological stages was confirmed.
Darwin’s Origin of Species implied a long past for man, and the acceptance of the idea of human evolution in the last four decades of the 19th century created a climate of thought in which archaeology flourished and that led to great advances in the unfolding of the full story of man’s development.
In his Pre-historic Times, Lubbock expanded the three-age system of Thomsen and Worsaae to a four-age system, dividing the Stone Age into Old and New periods (Paleolithic and Neolithic). In the last quarter of the 19th century remarkable Paleolithic discoveries were made in France and Spain; these included the discovery and authentication of actual works of sculpture and cave paintings from the Upper (later) Paleolithic Period (c. 30,000–c. 10,000 bce). When Marcellino de Sautuola discovered the cave paintings at Altamira, Spain (1875–80), most experts refused to believe they were Paleolithic; but after similar discoveries at Les Eyzies in France around 1900, they were accepted as such and were recognized as one of the most surprising and exciting archaeological discoveries. A succession of similar finds has continued in the 20th century. The most famous of these was at Lascaux, France, in 1940.
During the last quarter of the 19th century, Gen. A.H. Pitt-Rivers’ excavations of prehistoric and Roman sites at Cranborne Chase, Dorset, laid the foundations of modern scientific archaeological field technique, which was later developed and improved in England and Wales by men such as Sir Mortimer Wheeler and Sir Cyril Fox. Developments in the 20th century and beyond
The 20th century saw the extension of archaeology outside the areas of the Near East, the Mediterranean, and Europe, to other parts of the world. In the early ’20s, excavations at Mohenjo-Daro and Harappā, in present Pakistan, revealed the existence of the prehistoric Indus civilization. In the late ’20s, excavations at An-yang in eastern China established the existence of a prehistoric Chinese culture that could be identified with the Shang dynasty of early Chinese records.
The Stone Age has been described and studied throughout the world; among the most sensational discoveries are those of L.S.B. Leakey, who found stone tools and skeletal remains of early man dating back 2,000,000 years in the Olduvai Gorge in Tanzania. Intensive work of great importance has brought to light early Neolithic sites at Jericho in Palestine; Hassuna, Iraq; Çatalhüyük, Turkey; and elsewhere in the Near East, establishing the origins of agriculture in that region.
Serious archaeological work began later in America than Europe, but as early as 1784 Thomas Jefferson had excavated mounds in Virginia and made careful stratigraphical observations. The 20th century saw a great increase in archaeological knowledge about prehistoric America: two startling advances were the discovery of the origin of domesticated crops (including maize) in Central America and of the Olmec civilization of Mexico (1000–300 bce)—the oldest of the New World civilizations and probably the parent of all the others.
The enormous growth of archaeological work has meant the establishment of archaeology as an academic discipline; few important universities anywhere in the world are now without professors and departments of archaeology. There are now a very large number of scholarly journals in the field, as well as a considerable body of popularized books and journals that attempt to bridge the gap between professional and layman. Fieldwork Preliminary work
Some archaeologists call everything they do out-of-doors fieldwork, but others distinguish between fieldwork, in a narrower sense, and excavation. Fieldwork, in the narrow sense, consists of the discovery and recording of archaeological sites and their examination by methods other than the use of the spade and the trowel. Sites hitherto unknown are discovered by walking or motoring over the countryside: deliberate reconnaissance is an essential part of archaeological fieldwork.
In Europe, a study of old records and place-names may lead to the discovery of long-forgotten sites. The mapping of new and old sites is an essential part of archaeological survey. This process has been brought to a very high standard of perfection, both in the marking of archaeological sites on ordinary topographical maps and in the production of special period maps. The distribution map of artifacts, especially when studied against the background of the natural environment, is a key method of archaeological study.
The formerly earthbound archaeologist has been greatly helped by the development of aerial photography. The application of aerial photography to archaeological investigation began in a small way during World War I, as a side effect of military reconnaissance, and was given further impetus by World War II; the photographic intelligence departments of all the combatant nations were extensively staffed by archaeologists, who then carried their expertise and enthusiasm into the postwar years. The University of Cambridge now has its own department of air photography under J.K.S. St Joseph: using its own pilot and aircraft, it flies photographic missions over Ireland, Great Britain, Denmark, and The Netherlands. The number of new sites discovered each year by aerial photography is very large. Some of these are surface sites, especially partly destroyed sites that show up well in special conditions of light, as in early morning or late evening. But many are sites that could not be found on the ground and that show up in aerial photographs as variations in soil colour or in the density of crop.
Archaeological reconnaissance may be advanced from ordinary surface or aerial methods in a wide variety of ways. A very simple method is tapping the ground to sound for substructures and inequalities in the subsoil. Deep probes have made it possible to trace walls and ditches. The Lerici Foundation of Milan and Rome has had great success with this method since its development of the Nistri periscope, first used in 1957 in an Etruscan tomb in the cemetery of Monte Abbatone. The periscope is inserted into the burial chamber and can photograph the walls and contents of the whole tomb.