GeologyRocks

I've never heard of that before.  So....I am no help.  worthless post! 

A phacolith is an igneous body with an antiformal form (top and bottom surfaces concave downwards - convex up).

Think saddle-reef equivalent.

So what's the name for a synformal igneous body? Us geologists, have to name every little thing with something minutely different about it.

"A cactolith is a quasihorizontal chonolith composed of anastomosing ductoliths whose distal ends curl like a harpolith, thin like a sphenolith, or bulge discordantly like an akmolith or ethmolith."
link

Not sure but I think it might be lopolith

Geologists like a nappe between thrusts

According to wikipedia a phacolith is at the hinge of a fold so can be either antiformal or synformal.

I'm so glad I checked the link on this one - I originally though someone had got a greek dictionary for their birthday and just had to try it out!

Thanks, I think I am visualising what you are describing. Though isn't it strange that there doesn't appear to be a single diagram for one anywhere on the internet?!

My trusty old Longman Illustrated Dictionary of Geology has:

"Phacolith (noun)  an igneous intrusion in folded sedimentary rocks that is convex upwards and concave below" with a nice diagram.

I have made a rough sketch of a phacolith but don't know how to make it shew here! It is at /images/phacolith

All images, tutorials, articles, etc. are all reviewed before being published, hence why it couldn't be accessed. I've updated the image slightly and published it. Thanks for submitting it

Thanks Jon, btw, "pacoliths"? 

Ta for spotting the typo

Thanks! There is so much to learn..