The base of a basalt lava flow is seen some 30 cm below the hammer head. The lower part of the flow shows elongate vesicles (gas bubbles), which may have been stretched as the lava flowed. Above the hammer head, the lava is massive and non-vesicular. Below the basalt is a red breccia unit, representing the weathered top of an older basalt flow.
- What does the presence of this red, weathered horizon tell us about the nature and timing of the volcanic activity?
Scale: Hammer handle is 40 cm long.
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