Invisible links

Your example isn’t showing up for me, but searching your page source for
class="tumblr-widget-2"
should make it clear how to target the elements you want.

https://www.ncgea.org/tumblr-archive/
Sorry I gave the wrong link.

How do I access that element if I can’t find it in the Css, sorry for such trivial questions in new to editing WordPress sites. Thanks so far!

Try adding the following line at the bottom of the CSS file:

.Tumblr a {color: black;}