What is group dating
The compass only tilts forward and back so it must be rotated during this process; as a result, it is able to determine true inclination of the core sample.
Because the bubble is centred, the compass is level in both x and y.
Later on, back at the laboratory, we will carry out palaeointensity analysis on the samples.
The amount of magnetisation trapped in the rock is almost linearly related to the ancient magnetic field strength; because of this relationship, we are able obtain estimates for the strength of the ancient field.
This was not easy because much had changed in the When collecting samples, there are a number of considerations; 1) Because the remanence is only locked in to the rock as the rock cools below a certain temperature, the rock sample must also be kept cool whilst drilling it from the rock.
The image below shows Phil Mc Causland drilling a sample from an outcrop whilst Daniele Thallner pumps water through the drill and out of the end to keep the sample cool.
We take a sun sighting by turning the sun compass so that the sun casts a shadow though a small hole on to the fine line on the mirror, we then take a reading and record the time; this information is then put through some software to determine the X axis reading for the core sample.
To obtain the Y axis reading, we simply add 90 degrees.
Now, back in the lab, we have started the first measurements and are excited to uncover the rocks’ last secrets.
It’s that chance for a Palaeomagnetist to get from behind the desk and into, perhaps, a part of the world they have not seen before.
It was great to see the lovely skyline and the CN Tower (shown in the picture below) while every other person was dressed in blue, thanks to a home game of the Toronto Blue Jays.
At this point we would like to express our gratitude to Henry Halls, Phil Mc Causland and Joe Hodych for their help and contributions to get us started in our projects.
There, Henry awaited us with his treasure – drawers full of samples, floppy drives full of measurement data and an enormous amount of additional knowledge and kindly allowed us to use his samples and data for our projects.