Why not save your back and build a few raised beds? Pit digging sounds...unpleasant, and unless you're planning to plant a few trees with long taproots, possibly excessive. Most vegetables (and I'm generalizing here) will do fine with eighteen inches of topsoil, and four feet (in a raised bed or in a dug-out enriched pit) is certainly more than sufficient. You can certainly get away with even less than that: I've planted squash right in bags of compost on top of a gravel driveway, and they did just fine.

Your ravine is a different issue. If you've got an influx of non-native, invasive plants, are in a relatively isolated area, and can get a fire permit, you might consider a small, controlled burn. That will get rid of the problem plants and you'll likely see a return of some of your beautiful widflowers even without taking further steps. I'd be wary of planting general 'wildflower' mixes without looking at your state regulations, though, because many commercial mixes contain highly invasive plants or species labelled as noxious in domestic legislation.

I'd look into lasagna gardening. Basically, you put down layers of whatever organic matter you can get your hands on (autumn leaves shredded or not, grass clippings, compost, used coffee grounds, shredded paper, cardboard, sea weed, pine needles, finely shredded wood chips, sawdust, livestock manure and bedding, straw, etc.), keep it moist, and let weather and the natural process of decomposition do their thing. The worms and various other tiny critters will move in surprisingly quickly and work to incorporate your layers into the ground and in amongst themselves. The longer you allow it to sit, the deeper and more completely the soil will be improved. It really is amazing what can be accomplished with little to no work on your part. Check out the Soil, Compost, and Mulch Forum. You'll find more information than you ever thought possible on preparing soil for growing things. You'll also learn that the original soil preparation is the most critical stage in creating a beautiful garden or yard. You get better value in the end when you invest heavily in the beginning. Good luck.

Martha

Would it not be cheaper and less backbreaking to order in truckloads of good earth? or will this elevate your yard considerably.

if it's just small area you need to amend, do a double digging method. Instead of removing the material, incorporate good composted earth into the area. You can add brick sand, compost to break up clay. If you use livestock manure, make sure it's well composted otherwise it will contain live weed seeds. Also since it;s limestone area...the plants that will thrive there must be alkaline tolerant. There are probably a good number of meadow flowers that can grow in that area. Check for wildflower seeds in your area. Those would be suitable.

Composting is also the way to go in building up good soil.