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You are given layers A,F,D,H without knowing their relative or specific age. Write two ways you can know which layer is the oldest.

The simpliest way of knowing is when the layers are horizontal, the stratigraphy principle of superposition applies so the top layer is the youngest the bottom layer is the oldest. In a folded anticlyne form...
TT
Answered by Theodoros T. • Geology tutor
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What are the main differences between bivalves and brachiopods?

Bivalves - Firstly they have two identical valves make up the main shell. They also grow from a few mm to 1m in size such as the giant clam. In order to close the valves, a pair of adductor muscles contract ...
SB
Answered by Saskia B. • Geology tutor
14373 Views

During folding, how are joints formed in sandstone and cleavage formed in shale?

When beds undergo folding, the fold hinge stretches and experiences tension which can create extensional joints during compression. Often the fractures will infill with a mineral precipitate, forming a vein....
RM
Answered by Rhiannon M. • Geology tutor
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How are vesicles and amygdales formed in an igneous rock?

When a lava cools in forms air bubbles which can then burst. Leaving a hollow vesicle behind. Amygdales are vesciles infilled by minerals. Hydrothermal water with dissolved minerals pass through vesicles. As...
RC
Answered by Ruth C. • Geology tutor
4534 Views

How does magma form?

Magma can be described as melted rock deep within the Earth, usually originating from the melting of the upper mantle or crust. The magma will generally contain silica tetrahedra as well as many metal cation...
AB
Answered by Alfie B. • Geology tutor
31076 Views