<p>Observations of the internal structures of a sequence of lava flows in the Itsubo basaltic andesite unit of the Miocene Ogi Basalt provide new insights into the emplacement of modern jumbled sheet flows and pillow flows. The lower three lava flows are individually composed of the following lithofacies: massive sheet lavas, pillows, lava lobes, and hyaloclastite breccias. The massive sheet lavas have trough-shaped bases at their upstream ends and transform to platy sheets at the downstream ends of the upper two flows. These sheets have hyaloclastite breccias at the top and alternating foreset layers of pillows, lava lobes with lobe-surface breccias, and flow-foot breccias at the base. The sheet-top hyaloclastite breccias include fluidal clasts formed by ductile deformation of lava surfaces. The flow-foot breccias include steeply elongated fluidal clasts fed from the thin layers of pillows at the terminal feet of lava lobes, and large amoeboid pillows torn from the lobes, suggesting pulsating growth and detachment of lava from the lobes. The uppermost pillow flow consists of foreset-bedded pillow chains extending from the top of the flow, which are inferred to indicate strong pulses in lava supply. Sediment-filled depression in the pillowed flow may represent a channel emptied by drainage of molten lava into down-flow pillow chains. The lava flows of the Itsubo basaltic andesite unit are interpreted as a succession of flow units with various lava morphologies, analogous to modern jumbled sheet flows and terminal pillow flows, such as those reported from the 1998 eruption of Axial Seamount.</p>