materiały: Gilgai

Evidence: 100 • authority: 72

A gilgai is a small, ephemeral lake formed from a surface depression in expanding clay soils. Gilgai is also used to refer to the overall micro-relief in such areas, consisting of mounds and depressions. The word gilgai came into English from both Wiradjuri and Gamiliarraay languages. The pools are commonly a few metres across and less than 30 cm (12 in) deep but, in some instances, they may be several metres deep and up to 100 m (330 ft) across. Gilgais are found worldwide wherever there are cracking clay soils and marked wet and dry seasons. Gilgais are also called melonholes, crabholes, hogwallows, or puff and shelf formations.

Evidence: 43 • authority: 88

Some SH‐wave seismic reflections from depths of less than three metres. Shallow SH‐wave reflections are far from routine, although their study can provide insights into important properties of near‐surface materials that cannot be inferred from P‐wave data alone. Difficulties in separating SH‐wave reflections from Love waves are generally considered the major obstacle to progress in shallow SH‐wave seismic reflection. This may be the case in surveys undertaken at great depths, but it is not necessarily true for reflection data gathered at shallow and ultra‐shallow depths. This paper shows that when SH‐wave data possess wavelengths greater than the thickness of the superficial layer, Love wa…