Over 1600 feet, and another interesting intrusion

Today we processed rock core to over 1600 ft depth, mostly pahoehoe flows.  We didn't see any intrusive rock today, but yesterday we saw an intrusion with such interesting contacts that I decided to upload photos of them today:

The intrusion itself makes up most of the rock core piece shown in this photo, the more vesicular rock along the bottom of the image is a pahoehoe flow.  Note the irregular shape of the intrusive contact, particularly in the lower right corner where it surrounds a thin bit of pahoehoe lava.  Additionally, on the left side of the photo there is a piece of pahoehoe that was completely surrounded and separated from the rock it was part of before, a typical intrusive "capture" of the invaded rock.  As a side note, the darker areas of rock are mostly surface water that we weren't able to remove completely before taking the photo.  The edges of intrusions can also be dark even when dry though, as a result of rapid cooling to glass or extremely fine-grained material.  The other contact from the same intrusion illustrates this point:

The darker rock close to the contact is called a "chilled margin," and is often the first part of an intrusion to cool to solid rock.  The rest of the intrusion cools from its sides toward its center after magma has stopped flowing through (note elongate vesicles on the far right of the photo that indicate magma flow).