There are those who say that the unique geographical formation of Wadi Lajab is a wonder of nature.
The inexhaustible springs and the resulting luscious vegetation have their origin in a crater formed by volcanic and seismic activity in the area millions of years ago. 
Access to Wadi Lajab is through a pass on the eastern side of the Qahr mountain and after three kilometers with steep sides. Later the pass gradually widens to 30 meters and the Wadi Lajab appears between the two high rocky mountains.
The crater-like valley has running streams breaking occasionally into medium-sized waterfalls and around them is lush green vegetation. The steep mountain sides are covered with a green blanket of creepers and thick moss.  On the steep sides overhanging rocks and recesses covered with plants give it the impression of a hanging gardens. The height of the rocky sides varies between 300 and 800 meters.
The entry to the valley, just four to six meters wide, is sometimes exciting if not downright scary at times, especially in the rainy season. However, the locals know both the safe and and the dangerous spots in the valley.
The abundant flow of fresh water seeping through broken rocks on the mountain sides feeds the streams and keeps the area remarkably cool all year round.  There is a famous Arabic tragic love poem called "Layla Majnu" in which the hero Majnu bin Qais dies — a sort of Arabic Romeo and Juliet.
Local people believe that Manju came from this region.
Saudi historian Hadi Abu Amiriyah who has studied the Thamud people who lived in the Arabian Peninsula in ancient times believes that the she-camel, mentioned in the Qura'nic story of the Prophet Muhammad (PBUH) and his attempt to convert the Thamud, originated in the Raith mountains.