Meanwhile, after all that, I just found a tree on Ancestry.com that links an Isaac Garrison born 1799 in Plattekill, NY to father Isaac b. 1760, son of Major Richard Garrison b. 1727 in Westchester County, NY (Where the Isaac Garrison I mentioned earlier also lived), son of a Jonas Gerritsen b. 1684 in Westchester Co., NY, son of Derrick Gerritsen b. 1647 in NY (New Amsterdam at that time aka Manhattan). So it seems you have more than one trail to examine. My earlier comments might be totally off, but then, maybe these two lines are related, too.
I do believe Richie is correct you are most likely of Richard. I do have much on this Garrison line of you would like to contact me. If you are from my line I would like to add you to my tree :-)
Richie C.
Sep 3, 2009
Christine Garrison
Mar 24, 2010
Christine Garrison
Mar 25, 2010