Activity

Of course! Montbrook paleomagnetism sediment samples were collected throughout the section to compare results from the top and bottom. All sample orientations were recorded in the field as well as on the sample themselves (that’s the black arrow you see on the pictured sediment). Since we all know how crumbly the sand-dominated Montbrook sediments can be, a heavy coat of lacquer was applied to harden the sample as well as ‘lock’ in the position of sediment grains. Back in the lab (in this case, my garage), a diamond tipped rock saw is used to cut the larger samples into smaller ~2.3cm cubes (standard size for the machinery used to conduct paleomagnetic analysis). Ideally, each larger sample will be worked into 4 of these smaller cubes. Cubed samples are wrapped in tin foil for rigidity/protection while they are being stored!
-3 cubes are prepped to determine remanant paleomagnetic orientation, so it is essential that the direction of the black arrow from the larger sample translates over into these smaller samples. Why 3 samples? At least three samples are needed for analysis in order to be statistically significant. As with most things in science, the more repetitions/tested samples we can get, the better!
– 1 other sample is prepped and designated for composition analysis in order to test what minerals within the Montbrook sediment lend themselves to magnetization (ex: hematite/magnetite).

All in all, I have about 50 samples prepped. Paleomagnetism will not give us an exact age, but it is a great method to support the site’s estimated age which has been suggested strictly through vertebrate biochronology. With any luck, we may see a reversal in earth’s magnetic poles from the top of the geologic sequence from the bottom. If so (fingers crossed), this can be compared to well-documented magnetic records from the Late Miocene to further constrain the age of Montbrook!