As a graduate student, she began the first of a series of studies in the Fosdick Metamorphic Complex in Marie Byrd Land with her PhD advisor and project principal investigator Bruce Luyendyk.

Her work demonstrated a role for doming, anatexis, and intrusion, within a regional context of right lateral strike slip—leading to a model of rapid exhumation via transtension rather than an orthogonal extension as in a core complex.

The detachment fault of the core complex, when found, was discovered to display dextral oblique striae and constrictional fabrics[9][10] She continued to refine the fundamentals of the process of gneiss dome emplacement authoring a special publication on that topic by the Fosdick range as a type model.

[11] An outgrowth of the early work explored the Fosdick Mountains gneiss dome as a repository of information about crustal differentiation leading to stabilization of the landmass of Marie Byrd Land within the Antarctic continent.

[12] Siddoway aided the founding of the SCAR ANTscape project in 2009, which stimulated research leading to reconstruction of the bedrock topography of Antarctica for key intervals of the geologic past—an important parameter for understanding the origins and evolution of the Antarctic ice sheet.