| Author | Comment | Last activity | Moderation | ||
|---|---|---|---|---|---|
| marlokeno | "Thanks! " | Read more » | over 6 years ago | |||
| marlokeno | "OK, I found some promising links- https://www.jpl.nasa.gov/spaceimages/details.php?id=PIA21964 This link includes an example inset of part of San J..." | Read more » | over 6 years ago | |||
| marlokeno | "Hi- As noted above, chalk, e.g. chalk dust in classrooms, and cement manufacture, are major sources of calcium carbonate pollution. Cement manufac..." | Read more » | almost 7 years ago | |||
| marlokeno | " My first suggestion is to photograph on a cloudy day. Compensating for the sun is difficult. A polarizing filter helps, as does a uv filter, but ..." | Read more » | over 7 years ago |