For the most part, asphalt is generally obtained from petroleum. Most commercial applications of
asphalt are from petroleum-based asphalt. That doesn’t mean that natural asphalt isn’t used
popularly. Many large asphalt deposits exist in the world. This naturally occurring asphalt is usually
treated, mixed, or distilled before being sent for commercial use.


At its core, asphalt is simply the remains of diatoms and other living organisms that once thrived on
the ocean floor or beds of large lakes. As we know, organisms that got under the crushing weight of
many layers of soil have since transformed into materials like petroleum or kerogen due to the
temperature and pressure. Bitumen is another material that forms similarly.


The main deposits of asphalt are in lakes and seas, for example, the Pitch Lake in Trinidad and
Tobago, Lake Bermudez in Venezuela, the Dead Sea, and the La Brea Tar Pits. On the other hand,
there’s another kind of naturally-occurring bitumen. This type of bitumen occurs in unconsolidated
sandstones called oil sands in Alberta, Canada as well as in the tar sands in Utah, US.


All types of natural bitumen deposits are not equal. For example, Northern Alberta’s Athabasca oil
sands are the largest deposit of natural bitumen in the world and were formed in the early
Cretaceous period. These oil sands have up to 20% oil. On the other hand, the Uinta Basin in Utah,
US is 6% bitumen.


The Alberta deposits are surely the largest, but only a minority of these deposits are shallow enough
to be surface-mined. The majority of the Alberta deposits (around 80%) have to be produced by farreaching oil wells that leverage advanced techniques of extraction such as steam-assisted gravity
drainage.