The reported occurrence of agglutinated grains in the wall by the same authors remains unconvincing. (The words by the same authors should follow occurrence or the sentence should be rewritten: The same authors' report of the occurrence of agglutinated grains in the wall remains unconvincing.)
The writer began a detailed regional study of the Upper Cretaceous rocks of the area with fieldwork in 1980, when the Blackstone section was first studied in detail, with G.H. Turner. (The sentence should be rewritten: The writer began a detailed regional study of the Upper Cretaceous rocks of the area in 1980. During that field season the Blackstone section was first studied in detail by the writer and G.H. Turner.)