Thou hast set all the borders of the earth. The "borders of the earth" are the boundaries of land and sea, which are ascribed to God in Genesis 1:9 (comp. Job 26:10; Job 38:8; Psalms 33:7; Proverbs 8:29; Jeremiah 5:22).
Thou hast made summer and winter; literally, summer and winter thou didst form them; i.e. they are the result of thy arrangement of creation.