Note: cqlsh converts timestamps into current timezone
You can prove this manually:
$ cqlsh
cqlsh> CREATE KEYSPACE mykeyspace WITH REPLICATION = { 'class' : 'SimpleStrategy', 'replication_factor' : 1 };
cqlsh> use mykeyspace;
cqlsh> CREATE TABLE objects (id int PRIMARY KEY, name text, date timestamp);
cqlsh> INSERT INTO objects (id, name, date) VALUES (1, 'one', '2010-01-01T00:00:00Z');
cqlsh> SELECT * FROM objects;