Fossilization is the alteration of an organism’s remains, impressions or activities by physical, biological or chemical changes retaining the original material in some form. The two most common types of fossilization found within the Morden and District Museum are permineralization and replacement.

Permineralization or commonly petrification, occurs in porous material like wood, bones and shells. Bones are the most abundant type of fossil found in the area with a few large specimens of petrified wood. The organic material of an organism or plant is porous, containing holes within its structure. Once buried, supersaturated ground water supersaturated commonly with calcium carbonate or silica and in some instances gypsum or selenite, precipitates into the spaces or pores. After a duration of time and pressure, the minerals within the structure will stabilize and form the fossil we see today.

Replacement is the other common type of fossilization in the Morden area. In this instance the ground water will seep into the existing remains of an organism and dissolve it. At the same time the space left behind from the dissolved material may be filled in with other sediments or minerals such as silica or pyrite.

Preservation and Taphonomy

Fossil preservation preserves the remains or activities of organisms. Taphonomy is a process that describes the events taken place on an organism from the time of its death to its discovery as a fossil. Only the right circumstances can preserve an organism into a fossil.