Constructing pseudo-Anosovs from expanding interval maps

We investigate a phenomenon observed by W. Thurston wherein one constructs a pseudo-Anosov homeomorphism on the limit set of a certain lift of a piecewise-linear expanding interval map. We reconcile this construction with a special subclass of generalized pseudo-Anosovs, first defined by de Carvalho. From there we classify the circumstances under which this construction produces a pseudo-Anosov. As an application, we produce for each $g\ge 1$ a pseudo-Anosov ${\varphi }_g$ on the surface of genus $g$ that preserves an algebraically primitive translation structure and whose dilatation ${\lambda }_g$ is a Salem number.