Fossil Preparation

In past years, recovery of fossils was relatively easy due to the co-operation of the former local bentonite mining company, Pembina Mountain Clays. When a fossil was found it was carefully removed by trained museum personnel to ensure that it was not damaged during the recovery procedure.

Often the first view of what might be a major find is only a tiny fragment or small bone exposed by the bulldozers working at the mine. For the first step of its removal a large area around the find is excavated to determine the extent of the specimen. This is done with the aid of special tools. Picks and shovels are used to remove the heavy overburden of shale and bentonite and smaller tools, such as dental picks, brushes, and trowels are used for fine cleaning. When the entire fossil is exposed a trench is dug around it and the block is undercut, leaving the bones sitting on a pedestal slightly smaller than the block to be removed. If the fossil is very large it must be divided into several smaller blocks. At this point the specimen is photographed and a detailed site diagram is plotted with each bone numbered. If the fossil is especially fragile, "glyptal", a chemical hardener, is applied to the bones. At this stage the specimen is ready for the application of the "field jacket".

For the first stage in preparing the "field Jacket" a layer of wet paper towel is applied to the fossil. This serves to keep it separated from the plaster which is later applied and which becomes a "hard jacket." This part of the jacket is made of strips of burlap soaked in plaster of paris and then draped around the block starting at the bottom. Once the plaster jacket is dry and hardened, chisels are driven under the block to loosen it from the ground. The jacket is then quickly turned over and the fossil, still embedded undisturbed in the block, can then be safely transported to the Centre.

Later at the Centre, the matrix is removed, exposing the underside of the fossil. Then the fossil is carefully cleaned and, if necessary, receives further hardening with preservatives. Finally it is removed from the jacket and either put on display or classified and placed in drawers for storage. Each fossil is given a catalogue number which indicates what it is, and when and where it was found. An index card is then completed with all the information about the find, and is filed for future reference.

Fossils within the field jacket are situated in a matrix or rock, ensuring it doesn't move during transport.

In the lab the jacket is cut open with a saw. Using picks the rock layer (matrix) is removed to reveal the fossil. For finer work to remove hardened minerals from the outside of the fossil, microscopes and magnifying glasses are used in conjunction with an air scribe. The air scribe is a movable point that blows out air to remove finer material on the specimen.

Some specimens may require consolidant. The consolidant the MDM uses is B-76. This powder compound is dissolved in acetone for different consistencies. Application is primarily in the field and left to harden before removal. While preparing some fossils consolidant may be used inside the lab but must be left to harden over night. A consolidant acts like a glue from the inside out. The solution seeps into the fossil and begins hardening from the inside to the outside. This provides support and rigidity to the fossil. The fossils are prepared in such a way to leave them in their original state as much as possible.

Once prepared the fossils are ready for storage or display use.

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