What was Mohorovičić's observation?(1 point)

Question

Responses

Seismic waves travelled at constant speeds.
Seismic waves travelled at constant speeds.

Seismic waves penetrated all Earth's layers.
Seismic waves penetrated all Earth's layers.

Seismic waves could not go through the brittle crust.
Seismic waves could not go through the brittle crust.

Seismic waves travelled at varying speeds.

Answer 1

Mohorovičić's observation was that "Seismic waves travelled at varying speeds." This observation led to the identification of the Mohorovičić discontinuity (or Moho), which marks the boundary between the Earth's crust and the underlying mantle, where seismic wave speeds change significantly.

Answer 2

Which of the following are methods of relative aging of rocks? Select the three correct answers.(2 points)
Responses

cross-cutting relationships
cross-cutting relationships

original angularity
original angularity

superposition
superposition

original horizontality
original horizontality

radiometric dating
radiometric dating

angular relationships

Answer 3

The three methods of relative aging of rocks from the options provided are:

1. Cross-cutting relationships - This principle states that a geologic feature that cuts another is younger than the feature it cuts.

2. Superposition - In an undisturbed sequence of rocks, the oldest rocks are at the bottom, and the younger rocks are at the top.

3. Original horizontality - This principle states that layers of sediment are originally deposited horizontally under the action of gravity.

Radiometric dating is a method of absolute dating, not relative aging, and "angular relationships" is not a recognized method of relative dating in the same sense as the others listed.

So the correct answers are: cross-cutting relationships, superposition, and original horizontality.