During spring 1992, ice property, geophone, meteorological, and stress data were collected on first-year ice southwest of Cornwallis Island within the Canadian archipelago. One of the goals of the study was to specify the average characteristics of the ice, use these characteristics in a model of thermally induced stresses in the ice, and examine the fracturing associated with the occurrence of those stresses. The results of simulations with a thermal stress model indicate that stress variations within the ice can be reasonably approximated by a viscoelstic rheology. The rheology takes into consideration thermally induced strains generated locally as well as strains generated elsewhere and then mechanically transmitted through the ice. The geophone data showed both ice-borne and water-borne propagation paths for individual fracturing events. The data imply a detection radius out to 500--600 m for the ice-borne signatures of fractures. An investigation of a region after fracturing showed that (1) fracturing occurred in an area with a 10- to 15-cm snow cover, (2) the snow cover had been scored down to the surface of the ice, and (3) cracks in the ice were found under each location where the snow had been scored. The cracks were 5--6 m long and at least 15 cm deep. A review of these and other experimental results draw us to the conclusion that the forces required to produce fractures in response to natural forcing is greater for first-year floes than for multiyear floes. ¿ American Geophysical Union 1994