I have been going through the letters Ruth Cook refers to in the postings above. See: http://www.erwinbagpiper.com/mining_for_gold_II.htm
I am so greatfull to have this information as it brings so much light to the lives of these ancestors. I am a descendent of Joseph and Catherine (Cowan) Erwin and have working on a family book to bring the 40 years of research I have done on our family into a form that the family can understand.
That Mt. Holyoke was the name of a plantation makes the most sense to me. He owned 970 acres in the area and over 50 slaves so this would most certainly be considered a plantation.
I too would be interested in any additional information. I do know that James Cowan was a postmaster in Denver.
Thank you all! Kathy