Yes, the Apple support document HT207266 “Connect devices and displays with the Apple Thunderbolt 3 (USB-C) to Thunderbolt 2 Adapter” says you can do that.
I don’t know how fast Thunderbolt networking is in that case. The networking packets might not be allowed to use the full 10 Gbps bandwidth. For example, Thunderbolt 3 can transmit 40 Gbps, but PCIe transmission is maxed out at around 22 Gbps. I don’t know if network traffic falls under the PCIe limitation. DisplayPort traffic is separate and can use up to 32 Gbps on Thunderbolt 3. You can read about that in Thunderbolt3_TechBrief_FINAL.pdf at thunderbolttechnology.net
The macperformanceguide website has a very good review of Thunderbolt networking “Easy Thunderbolt Networking (10 Gigabit)”. Those tests used two Thunderbolt 2 Macs to achieve over 1000 MB/s but that occasionally dropped to under 100 MB/s. I guess Thunderbolt 1 would be half as fast. I don’t know if Thunderbolt networking has improved in the last two years.
