To make sense of this process the reader must first understand what amber is. This has been covered in another section of this web site, please go to What is Amber if you need to become familiar with this subject.
An inclusion in amber is an insect, plant or other object trapped in resin which oozed from trees millions of years ago. The circumstances through which inclusions are trapped in amber could be infinite; a leaf falling into a pool of resin, an insect trapped in a falling drop, a swarm of flies accidentally landing on the tacky bark of an ancient amber tree.
The type or form of amber can sometimes indicate how the resin was first laid down. Amber can be found which appears as though it were made from several layers progressively laid down one on top of the other. In this situation resin was exuded from the tree in the form of a flow. Each flow would progressively harden on the trunk or branch of the tree. As another flux of resin was discharged this would lie on top of the former gradually building up a series of layers which can be clearly seen in some ancient amber pieces. The type of amber is called Shelly amber.
Imagine now the ancient amber forest and the trunk of one of the many resin exuding trees. On the trunk is a layer of fresh resin (1 & 2) not yet hard but the surface tacky. This layer was formed from an exuded mass of resin gradually ebbing down the side of the tree.
An unlucky insect alights on the viscous face of the resin. Its feet adhere to the surface and before the animal can free its self another layer of resin flows down the tree and engulfs the insect.(3)
What happens next depends upon two key factors.
1. The resin remains intact, without becoming distorted through any number of destructive forces, examples of which would be compression, shearing, oxidation or heat.
2. The resin must find favourable conditions under which to mature, see the section relating to Resin into Amber.
The inclusion from the moment it is encased in resin undergoes a period of desiccation, all the water slowly leaves the body of the inclusion. If the body is completely encased in resin with no fractures leading to outer surface and the destructive effects of the air the internal structure of the insect can remain intact.
Dr David Grimaldi has published an interesting paper during 1994 in the American Museum Novitates, 3097, 31pp., 84 Figs. The paper entitled ‘Electron Microscopic Studies of Mummified Tissues in Amber Fossils’ shows the remarkable level of preservation of internal tissues which can be found in some inclusions, this includes amongst numerous other organs and body parts:
Flight muscle fibres and individual Cells. / Protocerebrum and axons (Brain). / Membranous air sacks / Tracheae and atrium.
It is from this material many scientists claim to have extracted viable ancient DNA. Look at this web sites section on DNA, Amber and Dinosaurs.
The internal organs are not preserved in every inclusion trapped in amber. Indeed in some cases the insect or plant is merely a shell, the interior is empty, the body structure has been completely dessicated and dried , attaching its self as a thin shell to the side of the body wall.
Cross Section Through the Thorax of an Ant Embedded in Amber
It is not uncommon to find insects which
occur on the surface of a cut or broken piece of amber.
In these cases the hollow shell of the inclusion can
sometimes be seen.
