Silver Creek Tunnel Diabase Sill
This is a duplicate of the RGM page 135 photo showing a diabase sill, almost 200 feet high, just at the east end of the Silver Cliff tunnel. The slightly lighter colored basalt is on the bottom; there would be additional layers (now mostly eroded away) above the diabase intrusion. It is mostly horizontal, but has a slightly upward tilt toward its east end. The even lighter pinkish zone is where the hot lava metamorphosed the top of the basalt.