| Term | Definition | Contributor | Modified |
|---|---|---|---|
| Blizzard | A severe weather condition characterized by reduced visibility from falling and/or blowing snow and strong winds that may be accompanied by low temperatures. | GCW Glossary | 2023.03.27 |
| Blizzards | No definition provided | Christopher Rauch | 2023.12.01 |
| BL Lacertae objects | No definition provided | Ryan McGranaghan | 2023.04.16 |
| block | Angular chunk of solid rock ejected during an eruption. | Ryan McGranaghan | 2023.04.16 |
| Blockade | No definition provided | Christopher Rauch | 2023.12.01 |
| Blockade, Pacific | No definition provided | Christopher Rauch | 2023.12.01 |
| Blockade running | No definition provided | Christopher Rauch | 2023.12.01 |
| Block-books | No definition provided | Christopher Rauch | 2023.12.01 |
| Blockbooks | No definition provided | Christopher Rauch | 2023.12.01 |
| Block-books--Facsimiles | No definition provided | Christopher Rauch | 2023.12.01 |
| Block field | A surficial layer of angular shattered rocks formed in either modern or Pleistocene periglacial environments | GCW Glossary | 2023.03.27 |
| blocking | No definition provided | Ryan McGranaghan | 2023.04.16 |
| blocking index | No definition provided | Ryan McGranaghan | 2023.04.16 |
| Blockite | No definition provided | Ryan McGranaghan | 2023.04.16 |
| Block-signal systems | No definition provided | Christopher Rauch | 2023.12.01 |
| Blocky iceberg | Sea ice terminology that describes a flat-topped iceberg with steep vertical sides. | GCW Glossary | 2023.03.27 |
| Blodite | No definition provided | Ryan McGranaghan | 2023.04.16 |
| Bloedite | No definition provided | Ryan McGranaghan | 2023.04.16 |
| Blomstrandite | No definition provided | Ryan McGranaghan | 2023.04.16 |
| Blood | No definition provided | Christopher Rauch | 2023.12.01 |