A couple popular hikes is one of two routes to Vogelsang High Sierra Camp. The quickest route there from Tuolumne Meadows is via Rafferty Creek, and can be done in about 4 hours. It mostly climbs up a long meadow to the camp. A more scenic route, and longer, is via Lyell Canyon and Ireland Creek. I've read that the Miwok Indians in Yosemite Valley used to meet at Ireland Lake and trade with the Paiute Indians living on the east side of the sierras. I imagine that obsidian would probably have been traded. There is at least one source of obsidian not far away from volcanic vents east of the park.

Once you reach Vogelsang you have a choice of two routes to Merced Lake. I like both, but if you chose to do the northern route I'd at least advise you to hike to Vogelsang Pass and check out the views. You won't regret it. The northern route has access to a couple nice lakes and passes through some pretty meadows. With either route the beating your body takes on the descent is worth it. Take your time and it won't be so bad.