31. These consist variously of sandstones, mudstones and siltstones . 32. The Thomson Formation has steeply dipping beds of greywacke, siltstone and slate. 33. The Paragua�u is composed of fine-grained sandstones, siltstones and argillites. 34. The group is a fluvial formation consisting primarily of red siltstones and sandstones. 35. It is primarily composed of hard sandstone with some inter-bedded siltstone . 36. The upper reaches of the watershed lie over siltstone . 37. The Irish Valley Member contains sandstone, siltstone , claystone, and shale. 38. Sandy siltstone and fine-grained sandstones are interbedded with the aforementioned rock types. 39. The lowest sediments in this formation are conglomerates, overlain by sandstones and siltstones . 40. It was the first dam constructed using tertiary sandstone and siltstone as fill materials.
