Low-temperature, basement-involved compressive folds are confined larg
ely to the hanging walls of thrust faults and appear to be produced in
response to both propagation and slip on non-planar faults. In this p
aper we develop a simple, two-dimensional, kinematic theory of basemen
t-involved structures capable of predicting much of their geometric co
mplexity and diversity. The theory is tested by applying it in the con
struction of retrodeformable cross sections and sequential kinematic m
odels of three structures-Willow Creek anticline, Big Thompson anticli
ne, and a small monocline on Casper Mountain-as well as less rigorous
comparison with several other well-constrained structures. Thrust faul
ts commonly propagate through the brittle upper crust along non-planar
paths due to interaction with inhomogeneities such as preexisting fau
lts or other zones of weakness, rock anisotropy, and/or effects of spa
cial or temporal stress field variability. The folding associated with
displacement on such a complex system of basement faults reduces conc
eptually to the behavior of a system of fault-fault-fold triple juncti
ons. A second key aspect of basement-involved structures is the respon
se of the stratified cover sequence in the evolving basement structure
. The main monocline in the stratified cover in many cases forms as a
drapefold over a triple junction in the basement. The model proposed h
ere presents a complex kinematic history for drape fold development. L
ayer-parallel shortening is predicted for the cover sequence of many t
riple junctions during early stages of deformation, whereas at later s
tages the cover experiences layer-parallel extension, especially in th
e steep limb and beneath the propagating fault. The cover strata in th
e steep limbs of monoclines we studied exhibit different stages in suc
h a kinematic sequence: (1) layer-parallel shortening with smaller-sca
le compressional folds (Rattlesnake Mountain anticline, Bighorn Mounta
ins, and Casper Mountain); (2) wedging (Willow Creek anticline); and (
3) layer-parallel extension (Big Thompson anticline, Rattlesnake Mount
ain anticline, and Banner Mountain).