Radioactive isotopes decay and they released heat, more heat was generated and earth was hotter than it is today.
Answer: B. Metamorphic rocks
Explanation: Metamorphic rocks are those that have undergone changes due to extreme heat and pressure. Thus, the rock, from which it becomes a metamorphic rock, is heated at temperatures above 150-200 ° and exposed to a pressure of 1500 bar. In this way, the structure of the rock is changed, in terms of the arrangement of the atoms, and the result is a change of physical and chemical properties. There are two basic types of metamorphic rocks: foliated and slate. Generally, some of the metamorphic rocks are anthracite, schist, quartzite, marble, etc.
Lake Erie and Lake Ontario
clear explanation and good explanation
