Window to the past
What is an amber ?
This is another type of fossilization where the organism is entrapped
in a biologically inert environment and it is preserved wholly. For the
insects, which frequently occur in this type of fossilization, "chitinous
skeletons are little altered, but the soft inner tissues are missing."
Many physical and chemical agents of abiotic environment such as the oxidative
air and temperature and biotic factors such as bacteria and scavengers
accelerate the decomposition of a dead organism. Avoidance of these factors
would aid in preserving the organism and eventually amber formation.
Amber is basically fossilized resin of a coniferous tree of early Tertiary
(about 70 million years or so). According to Poinar, resin is "complex
mixtures of terpenoid compounds, acids, and alcohols secreted from plant
parenchyma." One of the differences between resin and sap is the latter's
solubility in water since most of it is water from the xylem (water transporting
system) of the tree.
The process of amber formation
Basically, organisms fall or drop into it when resin first exudes out
of the tree due to its extreme stickiness. Oleoresins, essential oils,
compose most of the first deposited resin. It is volatile and is usually
lost through the years. Additional resin drops on top of it and gives the
organism a typical suspended appearance. Then the resin hardens and becomes
less vulnerable to destruction by the environment. Hardened resin has a
higher chance of being fossilized since it can resist the environment better
than pliable resin. The resin is hardened through a process called polymerization,
where "small molecules (monomers) combine chemically to produce a
large network of molecules." Hardened resin is called copal. This
is one of the factor necessary to produce amber.
As the copal ages, concentration of the essential oil decreases while
the copal progressively oxidizes the resin and polymerization continues.
The copal slowly turns into amber million years after the first entombment
of the organism. The only way to differentiate between the two elements
would be to put them through many physical and chemical tests such as UV
light testing, burning, and various other tests.
The most famous example is the amber from the Baltic Sea region (Germany,
Poland, Lithuania, Denmark, the former Soviet Union, Great Britain, Estonia,
Latvia, and Holland) where many organisms rarely found anywhere else in
the world from the Oligocene epoch from the Tertiary period occurred here.
Because of the presence of microscopic air bubbles, Baltic amber tend to
appear cloudy or milky with the hue varying with quantity and quality of
the microscopic air bubbles.
Amber || Casts & Molds
|| Compactions || Compressions
|| Coprolites & Gastroliths
Drying & Dessication || Freezing
|| Impressions || Molecular
Fossils || Permineralization
Reference || Trace
Fossils || Wax & Asphalt
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