Shells can be categorized as marine, estuarine, or riverine.
However, we recommend 50-100 milligrams be sent to allow for an aggressive cleaning prior to the dating (and repeat analyses if necessary for confirming results based on quality control measures, at no additional cost to the client).
Most shells, corals, and other carbonate materials are cleaned by physical abrasion to remove the outer surfaces and any adhering carbonate material and are then acid etched to remove approximately 10-30% or greater of the total weight so that only the good primary carbonate is dated.
The use of the shell’s carbonate component presents problems because the substance is soluble and may isotopically or chemically exchange with its environment.
When a shell exchanges carbon with soil acids around it, the shell’s carbon 14 ratio, and thus radiocarbon age, is altered.
You are welcome to contact us to discuss the pretreatment or request that we contact you after the pretreatment (and prior to dating).
– AMS dating requires as little as 3 milligrams of coral after the pretreatment.
In certain parts of the globe, the equatorial region in particular, deep waters move up.
This phenomenon is latitude dependent and occurs as a consequence of trade winds.
Carbon dioxide equilibrium between the atmosphere and surface waters is achieved relatively quickly.