Good job, Sam!
The top two pictures show the Crevices from the South (North at the top of the picture). The last photo is the entrance to what we called the Old Iron Mine located near the powerline on the Gertrude's Nose Trail, Northern End. I am searching hard but cannot come up with the name of the fellow adventurer -- how about some help here!
Exploring this crevice was an outlandish exploit. Jim Dahl, Bob Gastrock and I found it and followed the downward sloping floor until we came to the end: a jumble of rocks blocking the crevice itself. To my knowledge, that is as far as anyone ever got before us.
Since Jim was always the most adventurous (fool-hardy?) I will give him credit for suggesting that we try to climb over the fallen rocks to see if we could reach the other side. We stayed close to the wall on the left side following a ledge until we entered "The Chois" about 30 or 40 feet in the air. We wormed our way down until we couldn't go any further, at least I couldn't. Simply put, I was thicker than my cohorts.
Jim and Bob did go on and found that they were able to get to the back side of the fallen walls coming out about 50 feet in the air. Obviously, this was going to be a challenge!
We came back some time later with rope, carabiners, slings and (most importantly) a hammer and chisel. In the small confines of "the chois" we broke away a sharp ledge of rock so that I could make it to the other side. Once there, I tended the rope as Jim and Bob rappelled to the bottom and continued to explore. Their journey took them through the Shawangunk Grit to the shale layer below -- the only time I ever observed this.
Now, I was supposed to be able to get help if it was needed... but, as we left, we learned that the only way I could get out was to exhale as Jim pulled while Bob pushed. So much for leaving one guy to summon assistance!