One technique I remember was using the location of an object to date it, like how deep it was buried.

我记得有一种方法是利用物体的位置来确定它的年代，比如它被埋得有多深。

youdao

Every photo has two files: the photo itself (in JPEG format) and an XML description with the title, date, and location.

每幅照片有两个文件：照片本身(jpeg格式)和带有标题、日期和位置的XML描述。

youdao

All calendar entries show date, time, and location information.

所有日历条目都显示日期、时间和位置信息。

youdao

This search product is so powerful it can even serve up photos of your friends from a certain date or location.

FORBES: Mark Zuckerberg Unleashes Facebook Search To The World

Public authorities can obtain other communications data without the home secretary's authority, such as the time, date and location of phone calls.

BBC: How much privacy can smartphone owners expect?

In both cases the hosts created online invitations but sensibly ensured that any date and location information was only visible to invited guests.

FORBES: If you want to have a private party, don't invite your Foursquare-using friends