Ancient fern discovered in sonic core
Crews from Sonic Drilling Ltd. were amazed to discover a fossilized fern leaf in a recent core sample taken on a project in Tumbler Ridge, BC. The company had been contracted to drill to 160 ft., provide core samples and assist with soil penetration testing every five feet.
"The drillers just arbitrarily picked up a piece of the core sample and found the leaf inside," says Bill Fitzgerald, general manager of Sonic Drilling Ltd. "It was pretty exciting to see something that old." The engineer on site estimated the leaf to be approx. 80 million years old. It was cored at 160 feet below the surface and imbedded in coal.
Sonic drill rigs are often used on projects like this due to their ability to provide undisturbed, continuous core samples to 300 ft. and beyond. Using patented sonic drilling technology, samples, ranging from 3” to 8” in diameter, can be obtained from a variety of mixed materials (overburden) including boulders, clays, silt, sand and gravel – giving the sonic rig a distinct advantage over other types of drilling which often get jammed in overburden conditions.
Extruded into clear plastic sleeves and then neatly laid out, these core samples can be subjected to a detailed visual examination and analysis, followed by sampling, photographing and archiving for a permanent record of the existing conditions. Because they are undisturbed, continuous samples, any information remains where it was found in the sample.
As well, cased holes, provided by the sonic drilling technique, prevent the collapse of the borehole and ensure that cores are not contaminated by up-hole debris.