Purine and Pyrimidines in Sediments from the Experimental Mohole

Cytosine, adenine, guanine, and thymine, but not uracil, have been detected in core samples taken from various depths of the experimental Mohole. The following quantities of bases were found in the deepest core samples available (approximately 25 x 10(6) years old): cytosine, 2.5 microg/5 g; adenine, 0.9 microg/5 g; guanine, 0.2 micro/5 g; thymine and uracil, 0 microg/5 g.