What lies beneath the sand of the beaches and beneath the sand of the desert?

What marvels lay concealed beneath the granules of sand? The response to this inquiry varies significantly based on the geographical location. Some shifting sand dunes, propelled by the wind, could be hiding a multitude of secrets, including remnants of prehistoric forests. Sand itself is a product of weathered terrestrial rocks, worn down by rivers and other environmental elements over thousands, if not millions of years. Along the seashores, the ceaseless churning of the sea grinds rocks into sand. Digging into a beach could reveal layers of sandstone sedimentary rock, forged under pressure over time.

In contrast, most deserts are bare rock substrates, uncovered by sand. This rocky substrate, subjected to the desert's fluctuating temperatures during the day and night, expands, contracts, and cracks. Assisted by the wind that pelts the smaller stones, rocks are gradually eroded to sand over centuries. Excavating these areas could expose fresh rock substrate and clay deposits. Nomadic sand dunes can encapsulate and preserve anything they bury, as evidenced by the camelthorn trees in Namibia.

The Sahara, recognized as the world's largest desert, blankets a significant portion of Africa. Despite its imposing arid and hot environment, it is home to a plethora of unique features hidden under its sand-sea. One of these fascinating features is the labyrinth of subterranean rivers, or wadis. These concealed waterways, nourished by ancient aquifers, sustain numerous desert communities. 

Moreover, the Sahara is a treasure trove of minerals and natural resources. Mines extract gold, silver, copper, phosphates, uranium, and more, contributing to the economic growth of the region. Layered beneath the Sahara are also vestiges of human history. Archaeological sites preserve cave paintings, artifacts, and relics that provide glimpses into the lives of ancient Sahara inhabitants. Additionally, the subterranean features of the Sahara are of paramount interest to scientists. These geological attributes offer insights into the planet's evolution, the desert's formation, and contribute to our understanding of global climate change and geological dynamics.