Q 01/05

Which famous waterfall keeps retreating upstream because soft shale crumbles away beneath a hard dolomite cap?

A) Victoria Falls

B) Angel Falls

C) Iguazu Falls

D) Niagara Falls

Answer · why

D) Niagara Falls

Niagara Falls pours over tough Lockport dolomite resting on softer Rochester shale. The river wears the shale away until the unsupported cap breaks of...

Q 02/05

Heat and pressure deep underground turn shale into which harder rock, long split into roofing tiles and blackboards?

A) Marble

B) Slate

C) Soapstone

D) Granite

Answer · why

B) Slate

Slate is what shale becomes when metamorphism hardens it. It still splits into smooth, flat sheets, which is why it also tops billiard tables.

Q 03/05

Which South American country's giant shale oil and gas field is called Vaca Muerta, Spanish for dead cow?

A) Chile

B) Colombia

C) Argentina

D) Venezuela

Answer · why

C) Argentina

Argentina's Vaca Muerta lies beneath the Neuquén Basin in northern Patagonia. The country completed its first shale gas well there in 2010.

Q 04/05

Besides fossils and animal tracks, the flat bedding surfaces of shale sometimes preserve tiny craters left by what?

A) Raindrops

B) Lightning bolts

C) Falling leaves

D) Snowflakes

Answer · why

A) Raindrops

Raindrops that pitted soft mud long ago can survive as dimples once the mud hardens into shale. A single ancient shower can still be read on the rock,...

Q 05/05

Black shales that split into extremely thin sheets are nicknamed after which everyday material?

A) Glass

B) Paper

C) Leather

D) Cardboard

Answer · why

B) Paper

Paper shales peel apart like the pages of a book. Oily molecules stick to the faces of the mineral flakes and weaken the bonds between them, so the ro...