Biome/Before Beta 1.8

Biomes were introduced in Alpha 1.2.0, also known as the Halloween Update. The terrain generator and Biomes generator were majorly changed again in the Adventure Update, and again in 1.0.0.

Prior to the Halloween Update, a map had either a Snowy or Grassy theme which was randomly determined when creating the world. After the update, a world includes all biome themes generated in a distribution range that is determined from the biomes graph.

There were 13 biome types in 1.7: 10 in the Overworld, 1 in the Nether, and 2 unused ones that are in the code but aren't encountered in normal play.

The triangular-looking fern was rare, and only found in Rain Forest biome pre-1.8. At present, since Rain Forests removed entirely, ferns generate naturally since 1.2.1, where they spawn in the new jungle biomes.

World saves from before the Halloween and Adventure Updates
Worlds generated prior to the update remained unchanged except for changes in grass color. New chunks generated (by the player moving outside of the pre-biome world's generated bounds) do generate biomes, similar to the Nether being generated when you first enter it from a portal. Moving from 1.7.3 or earlier to 1.8 or later, the previous generated terrain stays the same but is in a different 1.8 biome. This is shown by the grass and leaf colors. A 1.7.3 forest biome could have the grass and leaf colors of a desert biome.

Taiga and Tundra biomes in Beta 1.8
In Beta 1.8, Notch said the Taiga and Tundra biomes would be left out until Beta 1.9 because of problems in the biome generation code, but it only concerns the snow weather and snow layers as the other common features of this type of land can still be generated. Tundra biome was readded in release 1.0, but Taiga didn't have snow before release 1.1.

Pre-1.8 Biomes
Before the Adventure Update, biomes were much smaller and less distinct. While there was less variation between different biomes, some players argue that the terrain within individual biomes was much more varied and interesting. Biome placement was controlled by temperature and humidity values, allowing interface biomes and making it impossible to generate desert near taiga or rainforest near tundra while making transitions from biome to biome smoother.

Beaches
Beaches are usually generated next to oceans or lakes and covered all nearby low elevated shorelines. Before Beta 1.8 they could be found in any biome. They came in two varieties: sand beach and gravel beach. Sandstone was located below sand in sand beaches. Gravel beaches had no such border and thus posed dangers like falling into caverns located right underneath them. Due to the changes in the terrain generation algorithm in the Beta 1.8 update beaches were removed completely from the game. Beaches were later re-added in 1.1.0, although this new version is not the same type as the ones generated before the Adventure Update. In 1.7 Gravel beaches, Stone beaches and Cold beaches are new variations of beaches

Cliffs
Cliffs are carved into hills, and sometimes have caves protruding into them. These caves contain the same blocks which one would find at the same layer in the hill they are carved out of. This may include Ores, Stone, Gravel, Sand, Sandstone and Dirt. As of Beta 1.8, these no longer generate randomly, but can be seen as part of the Extreme Hills biome. In 1.7, Extreme Hills biome were generated with snow at y=95 and other new variation.