Host granodiorite to the xenoliths on this page. This granodiorite contains large K-feldspar phenocrysts that have a weak preferred orientation.

This dark rock is the large xenolith that was undergoing fragmentation just prior to entrapment. The host granodiorite is visible to the left. The layered metamorphosed sedimentary xenolith has been injected by hundreds of dikelets of the host granodiorite parallel to the xenolith layering.

The granite dikelets thin and mostly vanish from one end of the xenolith to the other.

This is the southwest side of the xenolith, showing that the granodiorite dikelets are indeed extensions of the magma itself, visible at the top of the image.

The southwestern margin of the xenolith is covered with a ~40 cm thick rind of even-grained granodiorite in which K-feldspar phenocrysts are absent. It is from this material that the dikelets extend into the xenolith. The region outside of the rind (under the man on the right) is unusually K-feldspar-rich for ~1m outside of the rind before grading into the normal phenocrystic granodiorite.

This is another view of the xenolith (dark) southwestern margin, showing the rind rock (slightly right of center), and the K-feldspar phenocryst-rich rock (left). The K-feldspar-rich rock is not homogeneous, and contains patches (far left) that are very rich in K-feldspar phenocrysts.

Some are unusual patches occur in the rind that are apparently made up of shattered crystals, around which some dark lichen is growing to highlight the crystals. If there was any explanation of this texture I didn't hear it. I naively suggest that small regions of crystals shattered by sudden cooling as comparatively low-temperature steam escaped from the heating xenolith.

Eastern end of the xenolith, showing numerous shattered and fragmenting blocks trailing away from the large xenolith.

This closeup photo, in the block trail shown above, illustrates the very fine scale of xenolith fragmentation. The largest block shown here is ~30 cm long. Despite this small size, these blocks have been injected by granodiorite magma and have fragmented into pieces as thin as a few mm and lengths of a few cm. The guidebook describes the theoretically important fragmentation mechanisms that include thermal gradient cracking, thermal expansion mismatch cracking, and thermal anisotropy cracking. These would certainly be joined by stresses associated with metamorphism and fluid production during metamorphism of the xenolith block.

The end of a block in the trail to the east of the large xenolith. Here you can see the very thin and numerous dikelets of granodiorite that have been injected parallel to layering in the block, and that the block was, at some point, bent and broken.

A larger example of a bent and broken end to an elongate xenolithic block. Here again note the fine-scale injection of granodiorite dikelets parallel to layering.

Small swarm of xenoliths and K-feldspar phenocryst concentrations to the south of the large block in the images above. Note that the thin, dark line on the right is not a drip of water, but a very straight, thin xenolith.

The layered, metamorphosed Meguma Formation xenolith, from its interior where there are few granodiorite dikelets. Pelitic beds have abundant cordierite, which has weathered out as pits. The sandy beds are smooth. In some beds (not so clear here) sedimentary bedding structures can be seen in the sandy beds, including crossbedding.