Achuelean
Period belonging to the cultural beginning with the earliest chipped stone tools,
about 750,000 years ago,until the beginning of the Mesolithic Age,
about 15,000 years ago.
Ancestor
A plant or animal from which a species is descended.
Archeology
The systematic recovery and study of material evidence remaining from past human cultures.
Archaeological Excavations
Systematic recovery and study of material evidence—such as buildings, tools, and pottery—that
remains from past human life and culture.
Australopithecus
Australopithecus is a genus of extinct hominid (humanlike) fossils generally considered a possible
evolutionary ancestor of modern humans. Australopithecus came to the attention of the scientific
world in 1924 when Raymond Dart, a South African anatomy professor, was given the fossil skull
of a young child, found at Taung, Cape Province, South Africa. Although the teeth were shaped
differently from those of the apes and resembled those of modern humans, the brain of the Taung
child, even had it reached maturity, would have been no larger than that of a gorilla. Nevertheless,
Dart believed he had found the remains of an ancient hominid and named it Australopithecus
africanus, the "southern ape of Africa."
breccia.
Breccia is a type of rock composed of large angular fragments that have become cemented
together. Unlike the cobbles in conglomerates, which have been rounded by transport, the angular
fragments of breccias have been formed in place rather than by erosion and sedimentation.
Common in stratigraphic formations, they form in many ways: collapse of cave deposits, igneous
activity, disastrophism, and meteorite crater impacts. Nearly all rocks are subject to some natural
breakage, but they are considered breccias only when a considerable amount of fine-grained
cementing material (matrix) is produced during fragmentation.
Cave
Chamber beneath the surface of the earth or in the side of a hill, cliff, or mountain.
Caves vary in size and shape, and many have large openings to the surface.
Dolomite
A magnesia-rich sedimentary rock resembling limestone.
Evolution
Evolution is the process by which all living things have developed from primitive organisms through
changes occurring over billions of years, a progression that includes the most advanced animals and
plants. Exactly how evolution occurs is still a matter of debate, but that it occurs is a scientific fact.
Biologists agree that all living things arose through a long history of changes shaped by physical and
chemical processes that are still taking place. It is plausible that all organisms can be traced back to
the origin of LIFE from inanimate matter.
Excavation
To dig or hollow out.
To remove (soil) by digging.
To uncover by digging.
Extinct
No longer existing or living.
Fossil
A remnant or trace of an organism of a past geologic age, such as a skeleton or leaf imprint,
embedded in the earth's crust.
Mrs. Ples
The Most complete skeleton found of the specie Autralopithicus africanus. First called.
Plesianthropus.
Paleontropologist
Paleoanthropologists are concerned with reconstructing the evolutionary history and ways of life of
prehistoric Homo sapiens and of the extinct human species Homo erectus and Homo habilis.
They seek the origin of the genus Homo among the early hominids, or prehumans, and attempt to
trace the origin of the hominids among still earlier hominoid, or apelike, primates
Paleontropology
Prehistoric humans may be defined as the prehistoric populations of the living human species,
Homo sapiens, together with other, ancestral species of the genus Homo. The origins, evolution,
and cultural development of early humankind comprise the subject matter of the scholarly discipline
called paleoanthropology.
Quartz
Quartz, which is the most abundant SILICA MINERAL and which occurs in most igneous and
practically all metamorphic and sedimentary rocks, is nearly pure silicon dioxide. It has also been
found in some lunar rocks and meteorites. The name quartz is believed to have originated in the
early 1500s from the Saxon word querklufterz (cross-vein ore), which was corrupted to quererz
and then to quartz. Quartz was well known to the ancients, who called it crystal or rock crystal.
Quartz is colorless and transparent when pure. It is diamagnetic but does not conduct electricity. Its
hardness is 7 on the Mohs scale, and its specific gravity is 2.651. Quartz has no cleavage and fails
by brittle fracture; the fracture surfaces have vitreous luster.
Quartzite
The metamorphic rock quartzite is formed from sandstone or chert that has been heated and
recrystallized during metamorphic episodes such as regional deformation or contact with molten
rock. Exposed quartzites are resistant to weathering and commonly project as high hills and ridges.
Quartzite is of interest to geologists studying a region's geologic history because the rock retains
information about the type of rock it was before metamorphism and the type and stresses of the
metamorphic episode. Some of the textural features of the original sandstone or chert, such as the
shape and size of the grains and the type of bedding, are retained. Quartzite derived from
sandstone shows dust-like inclusions that can show the outlines of the original grains. Quartzite from
impure sandstones (containing mica or feldspar) may grade into other metamorphic rocks, such as
schist or gneiss. A mosaic of small grains is typical of quartzite derived from chert. If the chert had
alternating thin layers of silica and shaley material, the quartzite typically preserves this feature.
Quartzite formed during regional deformation shows the pressure or stress of metamorphism in
elongated and parallel quartz grains or in a preferred orientation of the crystallographic axes of
quartz grains of any shape.
Rand
The South African currency.
Species
A group of organisms in a population that are structurally similar and that can pass these similarities
on to their offspring through reproduction.
Stalactite & Stalagmite
Stalactites and stalagmites are formations found on the ceiling and floor, respectively, of a cave.
Groundwater seeping into a cave chamber contains carbon dioxide absorbed from the atmosphere
or the soil. The carbon dioxide may unite with limestone to form calcium bicarbonate, which also
may be dissolved and carried in the water percolating through the cave. When the water carrying
the calcium bicarbonate evaporates, it releases the carbon dioxide, and the remaining molecules are
normally deposited as crystals of calcium carbonate (calcite or aragonite).
If the crystals remain in contact with the ceiling they build up as a stalactite, a small, circular, hollow
tube. The water continues to flow down the center until the stalactite may be 1 m (3 ft) in length, or
longer, although stalactites are rarely more than 5 mm (0.2 in) in diameter. The presence of some
minerals such as copper or iron results in a colored stalactite.
Stalagmites are produced when water drops directly to the cave floor. The impact of the water
striking the floor causes it to break into droplets or into a film, releasing the excess carbon dioxide,
and the crystals begin to grow upward. If a stalactite and a stalagmite meet, they form a column.
Stalagmites are usually larger in diameter than stalactites, have rounded tops, and possess no
central canal. Some stalagmites are 10 m (33 ft) tall, and they can range up to 10 m in diameter.
The rate of growth of stalactites and stalagmites is not constant because it depends on water
percolation from the surface. The average rate of growth is approximately 2 mm (0.08 in) per year,
but so many variable factors are involved that their age cannot be determined in this way.
Water Table
The water table is the level in the ground below which the pores, or spaces, in the soil or rock are
saturated with water. It is also called the GROUNDWATER table or the waterline. Because of the
difficulty of determining the saturation level of material deep below the Earth's surface, the water
table is usually defined as the elevation of water surfaces in shallow, nonpumping wells, which
penetrate only short distances into the saturated zone. A water table is considered to be present
only where the uppermost saturated rocks are sufficiently permeable to yield well water. In areas
where the uppermost saturated rocks are too impermeable, deeper underlying beds that do yield
water are classified as being under confined conditions rather than water-table conditions.
- Encarta 97 -
- Grollier 96 -