Dissolve soda in sour cream; stir well. Set aside.
Cream butter in a large mixing bowl. Gradually add brown sugar; beat well. Add eggs, and beat well.
Combine flour, cinnamon, and nutmeg; stir in raisins and pecans to coat well. Add flour mixture and dissolved soda to creamed mixture, stirring until thoroughly blended.
Drop by teaspoonfuls 2 inches apart onto greased cookie sheets. Bake at 375° for 8 to 10 minutes. Remove from cookie sheets, and cool on wire racks.