Geological layers of the Witwatersrand Ridge (South Africa) about 100 metres from the <a href="//commons.wikimedia.org/wiki/Category:Witpoortjie_Falls" title="Category:Witpoortjie Falls">Witpoortjie Falls</a>. This site forms part of the northern limit of the <a href="https://en.wikipedia.org/wiki/Witwatersrand_Basin" class="extiw" title="en:Witwatersrand Basin">Witwatersrand Basin</a>. The light grey layers are <a href="https://en.wikipedia.org/wiki/Quartzite" class="extiw" title="en:Quartzite">quartzite</a> which was formed by sand being deposited in a shallow sea about 2,700 million years ago and the brown layers are <a href="https://en.wikipedia.org/wiki/Shale" class="extiw" title="en:Shale">shale</a> which was formed by mud that settled in deeper waters of the ancient seas. The ridge is within the <a href="https://en.wikipedia.org/wiki/Walter_Sisulu_National_Botanical_Garden" class="extiw" title="en:Walter Sisulu National Botanical Garden"> Walter Sisulu National Botanical Garden</a>
<a href="//commons.wikimedia.org/wiki/User:Martinvl" title="User:Martinvl">Martinvl</a>
<span class="int-own-work" lang="en">Own work</span>