Figure F33. Close-up photograph of medium-grained basalt from Unit 1 with sharp alteration zones paralleling the top and bottom (Sample 200-1224F-2R-1 [Piece 9, 32-40.5 cm]). The sample is a piece of oriented whole-round core; thus, these alteration zones were originally horizontal. The specimen was cored near a vertical fracture inferred from the narrow alteration zone on the right. The swirling pattern appears to represent alteration staining along a series of concentric microfractures. The later horizontal alteration zones at the top and bottom overprint the swirls.

Figure F33. Close-up photograph of medium-grained basalt from Unit 1 with sharp alteration zones paralleling the top and bottom (Sample 200-1224F-2R-1 [Piece 9, 32-40.5 cm]). The sample is a piece of oriented whole-round core; thus, these alteration zones were originally horizontal. The specimen was cored near a vertical fracture inferred from the narrow alteration zone on the right. The swirling pattern appears to represent alteration staining along a series of concentric microfractures. The later horizontal alteration zones at the top and bottom overprint the swirls.