A tale of two stones
The main architecture of Stonehenge consists of two distinct types of stone, sourced from completely different areas. The larger, more dominant stones are sarsens, a type of silicified sandstone. Geochemical analysis shows that 50 of the 52 remaining sarsens came from a specific area called West Woods, approximately 25 kilometers north of the monument. These large stones form the outer circle and the inner arrangement of five trilithons (two upright stones topped with a horizontal lintel). The uprights of the outer circle weigh around 25 tons each and stand about 4 meters high, while the largest trilithon uprights reach 9 meters and weigh over 40 tons.
The smaller stones are collectively known as bluestones. This term includes a variety of rock types, primarily dolerite and rhyolite. Their geological origin has been traced with high certainty to the Preseli Hills in Pembrokeshire, Wales—over 240 kilometers away. The bluestones, weighing between 2 and 5 tons, were arranged in different configurations inside the sarsen circle over the centuries. Radiocarbon dating suggests the first bluestones may have arrived as early as 3000 BCE, while the massive sarsens were erected between 2600 and 2400 BCE. The logistical challenge of transporting these multi-ton stones across such a great distance without modern technology is a subject of intense archaeological debate.