The Arecibo 430 MHz Incoherent Scatter Radar (ISR) has been used to observe vertical ionospheric electron concentration profiles in the 80--280 km altitude region at the highest sustained resolutions (150 m, 10 s) thus far reported for ion-line measurements. We present results that reveal layers and wave-like features in unprecedented detail and likely point to electrodynamic processes linking the E and F regions. Tidal Ion Layers (TILs) and sporadic E(Es) layers in the 100--110 km altitude region often display significant peaks and edges that appear in only one range gate (150 m). Also, previously unreported wave-like plasma structures-termed ion rain-with ~12 minutes apparent period, normalized amplitudes of 1--3%, and vertical wavelengths in excess of 30 km have been observed extending from base of the F-layer to the evening intermediate TIL with indications of coupling into the 90--110 km region below.¿ 1997 American Geophysical Union