Further, in 1913, Harvard advocated more study of Iapetus because some observations had revealed sudden and large, irregular brightness fluctuations. Attempts to explain Iapetus must contend with these horns of an historical dilemma. Plate 37 shows Iapetus exhibiting dichotomous facial topography adjacent to an active zone populated with circular and elongated light sources. Topography of Iapetus poses a scientific puzzlement in that two abruptly different surface compositions exist side by side. Water ice is thought to compose the light region, (1). The dark region, (2), is