Claystone.. hard pack.

I'm digging a site and it has extremely compacted clay and sand mix. It's extremely hard like frozen ground or pretty soft sandstone. I think it's called claystone. Anyway the biggest problem I think is cuz I'm working from below. And unlimited on digging force without lifting the front of the machine. So working from above reaching down I think I'd have more power. Working on the face All I can do for certain portions of the site. It's is just shaving at it. I stick the teeth in about an inch push down and curl off about 1 in material at a time which is ridiculously stupid and eats up teeth. I can't break large chunks off without getting the angles just right I switched too much smaller bucket but I simply can't penetrate the material with the smallish machine. I've got caterpillar bucket with penetration teeth. I got regular Hensley x156. And I got some 23 series rocking spade teeth. And none of them seem to work when I'm working from below. It's definitely not a mini machine. It's basically as powerful as a cat backhoe like a 410. But it's a little lighter and a lower horsepower. it's only like 70 horsepower and 20,000 lb. In the shaving scenario a 36-in bucket seems to do about the same as a 18-in bucket as far as depth so for productivity the more teeth the better. I'm trying to build a platform so I can work from above. And I usually dig deep every alternate bucket width. And then I can break large chunks off the in between projections. Anybody got any great techniques. Or recommended methods to actually move more material quickly.