A little background on Dr. Walter Peredery and a high level history on his contributions to geological research available at http://www.walkermineralogicalclub.com/clubhistorychronology.html (the following is a summary from this link and a few others):

Study of the Ringed Structure; Past, Present and Future -- Early in the 1990s, Robert S. Dietz, at the time a well-known respected geologist with the USGS, authored an article on the Sudbury astrobleme, published under the cover title "Mining an Asteroid". It makes a concise but strong case for the feasibility and probability of a direct deposit by a large asteroid-like object accounting for the majority of the "orebody" at Sudbury. The well-received article was a vindication of sorts for Dietz, who at one time could be described as the Rodney Dangerfield of his chosen profession.

After only rather preliminary study of the Sudbury superstructure early in his career in the early 1960s, Dietz was basically laughed out of the room at a geological conference for presenting his theory and opinion on the structure by stating that the site was in fact a very large ancient impact crater. The reaction of his admittedly more experienced peers motivated Dietz, who vowed to prove them wrong and therefore have the last laugh in so doing.

To achieve that goal Dietz teamed up with one Walter V. Peredery, a young and upcoming Canadian geologist who was also of the opinion that an impact origin for the Sudbury structure was a distinct probability. The rest, as they say, is history.

The interpretation of the oval shape structure that hosts the Sudbury deposit generated hot debates, but everything came to an end in 1963, when the U.S. geologist Robert Dietz, which at that time was working for NASA trying to put the first man on the Moon, recognized it as an impact structure. Well, not quite to an end, if we consider that in the early 1960s, Dietz was laughed out of the room at a geological conference when he tried to present its revolutionary theory. Later on, he teamed up with Walter Peredery, a young Canadian geologist and proved them all wrong.

1964 - Peredery & Dietz release the results of their studies, becoming the first to provide proof to the world of an impact origin for the Sudbury structure

In 1969, Mr. W. Peredery, student at the U.of T., spoke on “Evidence of Shock Metamorphism in the Sudbury Basin”.

The work of Peredery & Dietz has made the large contribution toward increasing our understanding of the structure and the materials contained -- scientifically speaking -- when it comes down to the subject of the Sudbury basin, the ringed structure, its mineralogy and their origin.

As an international team of equals, Peredery & Dietz were the first to locate, document, verify and confirm the existence & presence of shattercones and the shatterconing process across a wide area surrounding the outer perimeter of the structure. They identified many impact meltbodies & meltsheets, shock metamorphic features and related minerals in a range of locations at the ancient crash site. By the late 1960s, Peredery & Dietz had turned the tide of thought on the origin of not only the Sudbury basin and surrounding structure, but the huge mineral deposit within it as well.

Both Peredery & Dietz continued to study the Sudbury astrobleme independently through the 1970s and 80s, with Dietz concentrating on deep deposits of metals, while Peredery's main field of interest gravitated toward the study of surface meltbodies, metamorphism and the grey and black onaping members of the structure. Peredery also worked closely with NASA scientists and astronauts who visited, studied and gathered samples of impact related material from the site for comparison purposes with material present and future astronauts may recover or encounter from or around impact sites on the lunar surface.

To this day, the most thorough investigation of Sudbury astrobleme impact material is attributable to NASA. Since only minor impact related materials study of Sudbury specimens has taken place over the past two decades, it is apparent much more remains to be learned, not only from the subterranean metal-rich breccias and sulfides, but from surface feature materials such as the meltsheets, footwall breccia and the grey and black onaping fallback breccias of the Sudbury astrobleme as well.