A dyke (or dike) in geology is a type of later vertical rock between older layers of rock. Technically, it is any geologic body which cuts across:1  flat wall rock structures, such as bedding. dyke (or dike) in geology is a type of later vertical rock between older layers of rock. Technically, it is any geologic body which cuts across: 1  flat wall rock structures, such as bedding.
Another example would be the âdefault browserâ on your computer. Windows PCs come with Internet Explorer (the blue âEâ icon) as the default browser, just as Apple includes their own Safari browser as the default on their Mac computers.
Set the default email app and web browser on your Mac. When you click a link for an email address or a website, your Mac opens the app you've set for that kind of link. When you first set up your Mac, OS X sets Safari as the default browser for website links and Mail as the default email app.