I want to know the answer to the following question:
What ice age signaled the end of the normal climate in the Ordovician period?
All the background I'm provided with is that "The most-commonly accepted theory is that these events were triggered by the onset of an ice age, in the Hirnantian faunal stage that ended the long, stable greenhouse conditions typical of the Ordovician.". Is that enough to answer the question?
Answer: yes