 |
 |
|
|
|
 |
|
For more than 11,000 years, people have collected, traded, carved, and
examined amber; yet much about the substance remains a mystery. For
example, no one is certain how amber manages to preserve the organisms
entrapped in it (called "inclusions") so exquisitely. It is thought
that terpenes, compounds that become linked as the resin hardens, help
to preserve the inclusions by dehydrating the organisms and killing
any bacteria that might cause decay. Moreover, the organisms' tissues
do not shrink as they normally would during the dehydration process;
as a result their cellular structure remains intact, making amber
inclusions perfect for DNA study.
|
|
|
 |
|
Amber from the Cretaceous period, 65 to 140 million years ago, when
the
later dinosaurs flourished, offers some of the earliest glimpses of
many
life forms. During this period, flowering plants (now the dominant
life
form on earth) evolved along with bees, moths, and other symbiotic
insects.
Cretaceous amber, from extinct conifer trees, is brittle and fractures
easily.
Specimens of amber from the Cretaceous period can be found all over
the
world, with the largest deposit in Northern Russia. The Middle East
has the
oldest Cretaceous amber containing insects and other larger
organisms. In
Kuji, Japan, there are pieces of amber that are 85 million years old.
The
United States has several Cretaceous deposits, although only in New
Jersey
is amber found in appreciable quantities. Deposits there range in age
from
approximately 65 to 95 million years old.
|
This drawing depicts one of the most important insect fossils, the
oldest known bee, Trigona prisca, which is encapsulated in
amber from New Jersey. Although it dates from 65 to 80 million years
ago, this specimen belongs to a surprisingly recent evolutionary
group, raising questions about the corresponding evolution of
flowering plants.
|
The oldest known mushroom, Archaeomarasmius leggetti, found
in 90- to 94-million-year-old amber from New Jersey.
|
| |
|
|
 |
|
The world's largest amber deposits come from the shores of the Baltic
Sea, where amber has been harvested, traded, and crafted into
decorative objects for at least 13,000 years. The 400-square-mile
Samland Peninsula alone has produced ninety percent of all the amber
in Europe. Until the mid-nineteenth century, pieces of Baltic amber
were collected primarily from beaches. Since the 1850s, when
engineers began dredging and mining operations, millions of pounds of
Baltic amber have been mined.
|
|
|
A large piece of Baltic amber, left unpolished to show the natural
fissures, with a necklace of polished amber beads.
|
|
|
|
 |
|
Twenty-three- to thirty-million-year-old amber from the Dominican
Republic is prized for the diversity of inclusions it contains.
Dominican amber is mined chiefly to the north and east of Santiago,
where landslides reveal veins of lignite -- or blackened, fossilized
wood -- which accompany amber deposits. Using shovels and machetes,
the amber miners may burrow deep into mountains, sometimes forming
tunnels 100 to 200 feet long. Slightly softer than Baltic amber,
amber from the Dominican Republic was produced by a Hymenaea
tree, a now-extinct tree of the legume family. Dominican amber occurs
in several colors, including yellow and deep red, as well as the rarer
blue and smoky green.
|
|
|
The ant is a deep red because the body cavity is pyritized, a process
that occurs when inclusions trapped close to the surface are exposed
to minerals in the surrounding matrix.
|
|
|
|
 |
|
Among the dozens of major amber deposits scattered throughout the
world, most are from the Tertiary period, which dates from 1.6 to 65
million years ago. The deposits vary in age, botanical origin, color,
and composition, and occur on every continent except Antarctica. The
largest piece of transparent amber in the world, which weighs 33.5
pounds, comes from northern Myanmar, and is 40 to 50 million years
old. Sicilian amber -- deposits of which are much smaller -- is
approximately 20 million years old. The largest North American
deposit of Tertiary amber is in Arkansas.
|
|
|
  |
|
