Article of footwear with thermoformed siped sole structure

An article of footwear includes an upper coupled to a sole structure. The upper has a ground facing surface, and opposing medial and lateral sidewalls disposed on and extending from opposite medial and lateral sides of the ground facing surface. The sole structure is formed from a plurality of non-coextensive, thermoplastic foam layers, where each layer extends across a portion of the ground facing surface of the upper. These layers include at least a first foam layer and a second foam layer. The first foam layer has a different hardness and/or density than the second foam layer. Each of the first foam layer and the second foam layer extends into direct contact with, and is directly adhered to the lateral sidewall and the medial sidewall of the upper, and the first foam layer is secured to the second foam layer via an adhesive or a thermal weld.