Drilling at Rhynie

Drilling Rig

Above: Drilling rig at Rhynie in 1997. The drilling crew on the left  are removing a section of core barrel which encloses a 50mm diameter length of rock or 'core' taken from the Rhynie chert sequence.

One of the methods employed to sample the Rhynie chert together with the interbedded sedimentary rocks is to 'core' the rocks beneath the surface using a drilling rig (see inset above). If it is known, from previous work, the orientation in which the sedimentary rocks in the subsurface are tilting or 'dipping', the drill can be set at an angle that will be at or near to 900 to the dip of the rocks. This allows the maximum coverage of the sedimentary sequence cored (see inset below).

Drilling rig

Above: Diagrammatic section of a drilling rig set at an angle to recover 'rock core' at 900 to the dip of the sedimentary rocks in the subsurface.

Once recovered, the 'cores' of rock are marked with the respective drilling depth and are then transferred (in depth order) into specially designed boxes for storage and future study (see inset below).

Collecting core

Above: Cores of the Rhynie sequence recovered by drilling have been carefully marked and transferred into core boxes for storage and study back in the lab.

 

Other reasons for drilling?

From studying the cores of rock we can analyse not only the chert beds that may be present, but also the sedimentary rocks between the chert beds. In studying various aspects of the sedimentology we can assess many things, from the environment in which the sediments were deposited, to what happened to them after they were buried.

Drilling results help us to understand the stratigraphy of the sediments in the area - both in terms of the age and the 'sequence' in which the sediments were deposited. Another useful aspect of drilling a series of cores over a defined area, is that if we encounter the same chert beds within successive coring operations we can also assess the distribution or lateral continuity of the cherts over that area - in other words where individual chert beds occur and where they die out.

Over the years many cores have been taken through the sedimentary sequence at various localities in the Rhynie area. The drilling projects have provided hundreds of metres of rock core, much of it from the Dryden Flags Formation that contains the Rhynie chert. Drilling has also provided information on the other rock units in the area and on the geological structure of the area (Rice et al. 2002) (see the section on the Site Geology and Setting).

 

We would like to thank Hays Business Services for housing the cores taken from the Rhynie area at their core store in Aberdeen