Not by itself. Fieldwork is normal to geological practice, and carrying gear or operating equipment is incidental to it. What matters is whether the assignment as a whole involves professional geological judgement, or whether the applicant is being brought in mainly to execute tasks someone else designed and interprets.
Weigh the assignment as a whole
Take the full scope and ask what decisions the applicant makes: where to sample, how to log and classify, what the data indicate, what the report concludes. If those decisions belong to the applicant, the physical component is part of doing the work. If they belong to someone else and the applicant executes a set procedure, counsel should look at whether a different listing describes the role more accurately.
Hypothetical example: a drill-core logging supervisor spends most of each shift at the core shack, describing intervals, choosing sample intervals and approving the log that enters the database. Whether that work is requested as Geologist or as Scientific Technician/Technologist turns on whether the duties fit a profession that appears on the USMCA list and on the qualifications actually held; the title used on the site decides nothing. The useful test is who would be asked to defend the interpretation if a client disputed it.
If the answer is the applicant, describe the interpretive work first and the shift routine second. If the answer is a senior geologist who reviews every log, say so plainly and let counsel choose the listing that fits, because a letter overstating independence is harder to defend than one describing supervision accurately.