Java Edition:Gravel and Sand
Both gravel and sand were briefly discontinued during development between Infdev 20100227-1414 and Infdev 20100330-1511 after they were removed from natural generation. Both were recontinued in Infdev 20100413 when they were added back to the generation.
Obtaining
Mining
From Classic 0.0.14a to Indev 20100223, gravel and sand naturally generated in the world. The gravel and sand items can be obtained by simply mining them (since survival mode was introduced). Gravel and sand were missing in world generation from Infdev 20100227-1414 to Infdev 20100330-1511. Of these versions, only Infdev 20100327 and later can actually save. Gravel and sand are recontinued in Infdev 20100413 when they were added back to generation and both are still available as of 1.21.6 Release Candidate 1 (present).