Hello, I have a question for any landscapers or gardeners who might be able to help:

Background first: We have an area in our yard we wish to garden in, but the area has quite a bit of river gravel mixed into the top six to nine inches or so of the soil (used to have raised bed gardens with river stone paths). We have been digging out by hand, but that is thus far a quite slow and not overly efficient process. Our end goal is to till the area, slightly mound and amend the soil, and garden from there.

My Question: how to accomplish this as quickly as possible so as to still be able to have a spring-summer garden? Any advice would be very greatly appreciated! Thank you!