A gasket or seal member constructed of elastomeric material has at least one slot extending lengthwise of the member and across its thickness at an oblique angle to the sealing faces. There may be a plurality of slots spaced apart across the width of the member. In a preferred form of the invention multiple, parallel slots are formed at an oblique angle to the seal faces of the member forming branchiate-like layers of gasket material, in which each of the layers partially overlays at least one other layer.